diff --git a/tests/Composer/Test/Fixtures/installer/alias-solver-problems.test b/tests/Composer/Test/Fixtures/installer/alias-solver-problems.test
index 19d0ea287..7158057d1 100644
--- a/tests/Composer/Test/Fixtures/installer/alias-solver-problems.test
+++ b/tests/Composer/Test/Fixtures/installer/alias-solver-problems.test
@@ -6,8 +6,8 @@ Test the error output of solver problems with dev-master aliases.
         {
             "type": "package",
             "package": [
-                {"name": "a/a", "version": "dev-master", "require": {"d/d": "1.0.0"}},
-                {"name": "b/b", "version": "dev-master", "require": {"d/d": "2.0.0"}},
+                {"name": "a/a", "version": "dev-master", "require": {"d/d": "1.0.0"}, "default-branch": true},
+                {"name": "b/b", "version": "dev-master", "require": {"d/d": "2.0.0"}, "default-branch": true},
                 {"name": "d/d", "version": "1.0.0"},
                 {"name": "d/d", "version": "2.0.0"}
             ]
diff --git a/tests/Composer/Test/Fixtures/installer/alias-solver-problems2.test b/tests/Composer/Test/Fixtures/installer/alias-solver-problems2.test
index 2e3598ce2..d206764f2 100644
--- a/tests/Composer/Test/Fixtures/installer/alias-solver-problems2.test
+++ b/tests/Composer/Test/Fixtures/installer/alias-solver-problems2.test
@@ -6,7 +6,7 @@ Test the error output of solver problems with dev-master aliases.
         {
             "type": "package",
             "package": [
-                { "name": "locked/pkg", "version": "dev-master", "require": {"locked/dependency": "1.0.0"} }
+                { "name": "locked/pkg", "version": "dev-master", "require": {"locked/dependency": "1.0.0"}, "default-branch": true }
             ]
         }
     ],
@@ -18,7 +18,7 @@ Test the error output of solver problems with dev-master aliases.
 --LOCK--
 {
     "packages": [
-        { "name": "locked/pkg", "version": "dev-master", "require": {"locked/dependency": "1.0.0"} },
+        { "name": "locked/pkg", "version": "dev-master", "require": {"locked/dependency": "1.0.0"}, "default-branch": true },
         { "name": "locked/dependency", "version": "1.0.0" }
     ],
     "packages-dev": [],
diff --git a/tests/Composer/Test/Fixtures/installer/alias-with-reference.test b/tests/Composer/Test/Fixtures/installer/alias-with-reference.test
index 451e1f8b9..c37b6e5f3 100644
--- a/tests/Composer/Test/Fixtures/installer/alias-with-reference.test
+++ b/tests/Composer/Test/Fixtures/installer/alias-with-reference.test
@@ -8,7 +8,8 @@ Aliases of referenced packages work
             "package": [
                 {
                     "name": "a/aliased", "version": "dev-master",
-                    "source": { "reference": "orig", "type": "git", "url": "" }
+                    "source": { "reference": "orig", "type": "git", "url": "" },
+                    "default-branch": true
                 },
                 {
                     "name": "b/requirer", "version": "1.0.0",
@@ -31,7 +32,8 @@ update
         {
             "name": "a/aliased", "version": "dev-master",
             "source": { "reference": "abcd", "type": "git", "url": "" },
-            "type": "library"
+            "type": "library",
+            "default-branch": true
         },
         {
             "name": "b/requirer", "version": "1.0.0",
diff --git a/tests/Composer/Test/Fixtures/installer/aliased-priority-conflicting.test b/tests/Composer/Test/Fixtures/installer/aliased-priority-conflicting.test
index c13d5fc0e..b409a5cfc 100644
--- a/tests/Composer/Test/Fixtures/installer/aliased-priority-conflicting.test
+++ b/tests/Composer/Test/Fixtures/installer/aliased-priority-conflicting.test
@@ -13,20 +13,24 @@ Aliases take precedence over default package even if default is selected
                 {
                     "name": "a/req", "version": "dev-master",
                     "extra": { "branch-alias": { "dev-master": "1.0.x-dev" } },
-                    "source": { "reference": "forked", "type": "git", "url": "" }
+                    "source": { "reference": "forked", "type": "git", "url": "" },
+                    "default-branch": true
                 },
                 {
                     "name": "a/req", "version": "dev-master",
                     "extra": { "branch-alias": { "dev-master": "1.0.x-dev" } },
-                    "source": { "reference": "master", "type": "git", "url": "" }
+                    "source": { "reference": "master", "type": "git", "url": "" },
+                    "default-branch": true
                 },
                 {
                     "name": "a/a", "version": "dev-master",
-                    "require": { "a/req": "dev-master" }
+                    "require": { "a/req": "dev-master" },
+                    "default-branch": true
                 },
                 {
                     "name": "a/b", "version": "dev-master",
-                    "require": { "a/req": "dev-master" }
+                    "require": { "a/req": "dev-master" },
+                    "default-branch": true
                 }
             ]
         }
@@ -44,12 +48,14 @@ Aliases take precedence over default package even if default is selected
         {
             "name": "a/a", "version": "dev-master",
             "require": { "a/req": "dev-master" },
-            "type": "library"
+            "type": "library",
+            "default-branch": true
         },
         {
             "name": "a/b", "version": "dev-master",
             "require": { "a/req": "dev-master" },
-            "type": "library"
+            "type": "library",
+            "default-branch": true
         },
         {
             "name": "a/req", "version": "dev-feature-foo",
diff --git a/tests/Composer/Test/Fixtures/installer/install-aliased-alias.test b/tests/Composer/Test/Fixtures/installer/install-aliased-alias.test
index 6fd1f7b53..c8070275c 100644
--- a/tests/Composer/Test/Fixtures/installer/install-aliased-alias.test
+++ b/tests/Composer/Test/Fixtures/installer/install-aliased-alias.test
@@ -11,7 +11,8 @@ Installing double aliased package
                     "dist": { "type": "file", "url": "" },
                     "require": {
                         "b/b": "dev-master"
-                    }
+                    },
+                    "default-branch": true
                 },
                 {
                     "name": "b/b", "version": "dev-foo",
diff --git a/tests/Composer/Test/Fixtures/installer/install-dev-using-dist.test b/tests/Composer/Test/Fixtures/installer/install-dev-using-dist.test
index 400e932ed..4cb2dbbb5 100644
--- a/tests/Composer/Test/Fixtures/installer/install-dev-using-dist.test
+++ b/tests/Composer/Test/Fixtures/installer/install-dev-using-dist.test
@@ -14,7 +14,8 @@ Installs a dev package from lock using dist
                         "type": "zip",
                         "url": "http://www.example.com/dist.zip",
                         "reference": "459720ff3b74ee0c0d159277c6f2f5df89d8a4f6"
-                    }
+                    },
+                    "default-branch": true
                 }
             ]
         }
@@ -37,7 +38,8 @@ install --prefer-dist
                 "url": "http://www.example.com/dist.zip",
                 "reference": "459720ff3b74ee0c0d159277c6f2f5df89d8a4f6"
             },
-            "type": "library"
+            "type": "library",
+            "default-branch": true
         }
     ],
     "packages-dev": [],
diff --git a/tests/Composer/Test/Fixtures/installer/install-reference.test b/tests/Composer/Test/Fixtures/installer/install-reference.test
index 74bf6e40a..33e7f5946 100644
--- a/tests/Composer/Test/Fixtures/installer/install-reference.test
+++ b/tests/Composer/Test/Fixtures/installer/install-reference.test
@@ -7,18 +7,19 @@ Installs a dev package forcing it's reference
             "type": "package",
             "package": [
                 {
-                    "name": "a/a", "version": "dev-master",
-                    "source": { "reference": "abc123", "url": "", "type": "git" }
+                    "name": "a/a", "version": "dev-main",
+                    "source": { "reference": "abc123", "url": "", "type": "git" },
+                    "default-branch": true
                 }
             ]
         }
     ],
     "require": {
-        "a/a": "dev-master#def000"
+        "a/a": "dev-main#def000"
     }
 }
 --RUN--
 install
 --EXPECT--
-Installing a/a (dev-master def000)
-Marking a/a (9999999-dev def000) as installed, alias of a/a (dev-master def000)
+Installing a/a (dev-main def000)
+Marking a/a (9999999-dev def000) as installed, alias of a/a (dev-main def000)
diff --git a/tests/Composer/Test/Fixtures/installer/unbounded-conflict-does-not-match-dev-master.test b/tests/Composer/Test/Fixtures/installer/unbounded-conflict-does-not-match-dev-master.test
index 6997e5a77..900028457 100644
--- a/tests/Composer/Test/Fixtures/installer/unbounded-conflict-does-not-match-dev-master.test
+++ b/tests/Composer/Test/Fixtures/installer/unbounded-conflict-does-not-match-dev-master.test
@@ -7,7 +7,7 @@ Test that a conflict against >=5 does not include dev-master or other dev-x
             "type": "package",
             "package": [
                 { "name": "conflicter/pkg", "version": "1.0.0", "conflict": { "victim/pkg": ">=5", "victim/pkg2": ">=5" } },
-                { "name": "victim/pkg", "version": "dev-master" },
+                { "name": "victim/pkg", "version": "dev-master", "default-branch": true },
                 { "name": "victim/pkg2", "version": "dev-foo" }
             ]
         }
diff --git a/tests/Composer/Test/Fixtures/installer/update-changes-url.test b/tests/Composer/Test/Fixtures/installer/update-changes-url.test
index 521b5611a..15600aefe 100644
--- a/tests/Composer/Test/Fixtures/installer/update-changes-url.test
+++ b/tests/Composer/Test/Fixtures/installer/update-changes-url.test
@@ -17,7 +17,8 @@ g/g is dev and installed in a different ref than the #ref, so it gets updated an
                 {
                     "name": "a/a", "version": "dev-master",
                     "source": { "reference": "2222222222222222222222222222222222222222", "url": "https://github.com/a/newa", "type": "git" },
-                    "dist": { "reference": "2222222222222222222222222222222222222222", "url": "https://api.github.com/repos/a/newa/tarball/2222222222222222222222222222222222222222", "type": "tar", "shasum": "newsum" }
+                    "dist": { "reference": "2222222222222222222222222222222222222222", "url": "https://api.github.com/repos/a/newa/tarball/2222222222222222222222222222222222222222", "type": "tar", "shasum": "newsum" },
+                    "default-branch": true
                 },
                 {
                     "name": "b/b", "version": "2.0.3",
@@ -32,23 +33,27 @@ g/g is dev and installed in a different ref than the #ref, so it gets updated an
                 {
                     "name": "d/d", "version": "dev-master",
                     "source": { "reference": "2222222222222222222222222222222222222222", "url": "https://github.com/d/newd", "type": "git" },
-                    "dist": { "reference": "2222222222222222222222222222222222222222", "url": "https://api.github.com/repos/d/newd/tarball/2222222222222222222222222222222222222222", "type": "tar", "shasum": "newsum" }
+                    "dist": { "reference": "2222222222222222222222222222222222222222", "url": "https://api.github.com/repos/d/newd/tarball/2222222222222222222222222222222222222222", "type": "tar", "shasum": "newsum" },
+                    "default-branch": true
                 },
                 {
                     "name": "e/e", "version": "dev-master",
                     "source": { "reference": "2222222222222222222222222222222222222222", "url": "https://github.com/e/newe", "type": "git" },
-                    "dist": { "reference": "2222222222222222222222222222222222222222", "url": "https://api.github.com/repos/e/newe/tarball/2222222222222222222222222222222222222222", "type": "tar", "shasum": "newsum" }
+                    "dist": { "reference": "2222222222222222222222222222222222222222", "url": "https://api.github.com/repos/e/newe/tarball/2222222222222222222222222222222222222222", "type": "tar", "shasum": "newsum" },
+                    "default-branch": true
                 },
                 {
                     "name": "f/f", "version": "dev-master",
                     "source": { "reference": "2222222222222222222222222222222222222222", "url": "https://github.com/f/newf", "type": "git" },
                     "dist": { "reference": "2222222222222222222222222222222222222222", "url": "https://api.github.com/repos/f/newf/tarball/2222222222222222222222222222222222222222", "type": "tar", "shasum": "newsum" },
-                    "transport-options": { "foo": "bar2" }
+                    "transport-options": { "foo": "bar2" },
+                    "default-branch": true
                 },
                 {
                     "name": "g/g", "version": "dev-master",
                     "source": { "reference": "2222222222222222222222222222222222222222", "url": "https://github.com/g/newg", "type": "git" },
-                    "dist": { "reference": "2222222222222222222222222222222222222222", "url": "https://api.github.com/repos/g/newg/tarball/2222222222222222222222222222222222222222", "type": "tar", "shasum": "newsum" }
+                    "dist": { "reference": "2222222222222222222222222222222222222222", "url": "https://api.github.com/repos/g/newg/tarball/2222222222222222222222222222222222222222", "type": "tar", "shasum": "newsum" },
+                    "default-branch": true
                 }
             ]
         }
@@ -68,7 +73,8 @@ g/g is dev and installed in a different ref than the #ref, so it gets updated an
     {
         "name": "a/a", "version": "dev-master",
         "source": { "reference": "1111111111111111111111111111111111111111", "url": "https://github.com/a/a", "type": "git" },
-        "dist": { "reference": "1111111111111111111111111111111111111111", "url": "https://api.github.com/repos/a/a/zipball/1111111111111111111111111111111111111111", "type": "zip", "shasum": "oldsum" }
+        "dist": { "reference": "1111111111111111111111111111111111111111", "url": "https://api.github.com/repos/a/a/zipball/1111111111111111111111111111111111111111", "type": "zip", "shasum": "oldsum" },
+        "default-branch": true
     },
     {
         "name": "b/b", "version": "2.0.3",
@@ -83,19 +89,22 @@ g/g is dev and installed in a different ref than the #ref, so it gets updated an
     {
         "name": "d/d", "version": "dev-master",
         "source": { "reference": "1111111111111111111111111111111111111111", "url": "https://github.com/d/d", "type": "git" },
-        "dist": { "reference": "1111111111111111111111111111111111111111", "url": "https://api.github.com/repos/d/d/zipball/1111111111111111111111111111111111111111", "type": "zip", "shasum": "oldsum" }
+        "dist": { "reference": "1111111111111111111111111111111111111111", "url": "https://api.github.com/repos/d/d/zipball/1111111111111111111111111111111111111111", "type": "zip", "shasum": "oldsum" },
+        "default-branch": true
     },
     {
         "name": "f/f", "version": "dev-master",
         "source": { "reference": "1111111111111111111111111111111111111111", "url": "https://github.com/f/f", "type": "git" },
         "dist": { "reference": "1111111111111111111111111111111111111111", "url": "https://api.github.com/repos/f/f/zipball/1111111111111111111111111111111111111111", "type": "zip", "shasum": "oldsum" },
-        "transport-options": { "foo": "bar" }
+        "transport-options": { "foo": "bar" },
+        "default-branch": true
     },
     {
         "name": "g/g", "version": "dev-master",
         "source": { "reference": "0000000000000000000000000000000000000000", "url": "https://github.com/g/g", "type": "git" },
         "dist": { "reference": "0000000000000000000000000000000000000000", "url": "https://api.github.com/repos/g/g/zipball/0000000000000000000000000000000000000000", "type": "zip", "shasum": "oldsum" },
-        "transport-options": { "foo": "bar" }
+        "transport-options": { "foo": "bar" },
+        "default-branch": true
     }
 ]
 --LOCK--
@@ -105,7 +114,8 @@ g/g is dev and installed in a different ref than the #ref, so it gets updated an
             "name": "a/a", "version": "dev-master",
             "source": { "reference": "1111111111111111111111111111111111111111", "url": "https://github.com/a/a", "type": "git" },
             "dist": { "reference": "1111111111111111111111111111111111111111", "url": "https://api.github.com/repos/a/a/zipball/1111111111111111111111111111111111111111", "type": "zip", "shasum": "oldsum" },
-            "type": "library"
+            "type": "library",
+            "default-branch": true
         },
         {
             "name": "b/b", "version": "2.0.3",
@@ -123,21 +133,24 @@ g/g is dev and installed in a different ref than the #ref, so it gets updated an
             "name": "d/d", "version": "dev-master",
             "source": { "reference": "1111111111111111111111111111111111111111", "url": "https://github.com/d/d", "type": "git" },
             "dist": { "reference": "1111111111111111111111111111111111111111", "url": "https://api.github.com/repos/d/d/zipball/1111111111111111111111111111111111111111", "type": "zip", "shasum": "oldsum" },
-            "type": "library"
+            "type": "library",
+            "default-branch": true
         },
         {
             "name": "f/f", "version": "dev-master",
             "source": { "reference": "1111111111111111111111111111111111111111", "url": "https://github.com/f/f", "type": "git" },
             "dist": { "reference": "1111111111111111111111111111111111111111", "url": "https://api.github.com/repos/f/f/zipball/1111111111111111111111111111111111111111", "type": "zip", "shasum": "oldsum" },
             "type": "library",
-            "transport-options": { "foo": "bar" }
+            "transport-options": { "foo": "bar" },
+            "default-branch": true
         },
         {
             "name": "g/g", "version": "dev-master",
             "source": { "reference": "0000000000000000000000000000000000000000", "url": "https://github.com/g/g", "type": "git" },
             "dist": { "reference": "0000000000000000000000000000000000000000", "url": "https://api.github.com/repos/g/g/zipball/0000000000000000000000000000000000000000", "type": "zip", "shasum": "oldsum" },
             "type": "library",
-            "transport-options": { "foo": "bar" }
+            "transport-options": { "foo": "bar" },
+            "default-branch": true
         }
     ],
     "packages-dev": [],
@@ -156,7 +169,8 @@ g/g is dev and installed in a different ref than the #ref, so it gets updated an
             "name": "a/a", "version": "dev-master",
             "source": { "reference": "2222222222222222222222222222222222222222", "url": "https://github.com/a/newa", "type": "git" },
             "dist": { "reference": "2222222222222222222222222222222222222222", "url": "https://api.github.com/repos/a/newa/tarball/2222222222222222222222222222222222222222", "type": "tar", "shasum": "newsum" },
-            "type": "library"
+            "type": "library",
+            "default-branch": true
         },
         {
             "name": "b/b", "version": "2.0.3",
@@ -174,26 +188,30 @@ g/g is dev and installed in a different ref than the #ref, so it gets updated an
             "name": "d/d", "version": "dev-master",
             "source": { "reference": "1111111111111111111111111111111111111111", "url": "https://github.com/d/newd", "type": "git" },
             "dist": { "reference": "1111111111111111111111111111111111111111", "url": "https://api.github.com/repos/d/newd/tarball/1111111111111111111111111111111111111111", "type": "tar", "shasum": "newsum" },
-            "type": "library"
+            "type": "library",
+            "default-branch": true
         },
         {
             "name": "e/e", "version": "dev-master",
             "source": { "reference": "1111111111111111111111111111111111111111", "url": "https://github.com/e/newe", "type": "git" },
             "dist": { "reference": "1111111111111111111111111111111111111111", "url": "https://api.github.com/repos/e/newe/tarball/1111111111111111111111111111111111111111", "type": "tar", "shasum": "newsum" },
-            "type": "library"
+            "type": "library",
+            "default-branch": true
         },
         {
             "name": "f/f", "version": "dev-master",
             "source": { "reference": "1111111111111111111111111111111111111111", "url": "https://github.com/f/f", "type": "git" },
             "dist": { "reference": "1111111111111111111111111111111111111111", "url": "https://api.github.com/repos/f/f/zipball/1111111111111111111111111111111111111111", "type": "zip", "shasum": "oldsum" },
             "type": "library",
-            "transport-options": { "foo": "bar" }
+            "transport-options": { "foo": "bar" },
+            "default-branch": true
         },
         {
             "name": "g/g", "version": "dev-master",
             "source": { "reference": "1111111111111111111111111111111111111111", "url": "https://github.com/g/newg", "type": "git" },
             "dist": { "reference": "1111111111111111111111111111111111111111", "url": "https://api.github.com/repos/g/newg/tarball/1111111111111111111111111111111111111111", "type": "tar", "shasum": "newsum" },
-            "type": "library"
+            "type": "library",
+            "default-branch": true
         }
     ],
     "packages-dev": [],
diff --git a/tests/Composer/Test/Fixtures/installer/update-dev-to-new-ref-picks-up-changes.test b/tests/Composer/Test/Fixtures/installer/update-dev-to-new-ref-picks-up-changes.test
index 181e039ea..7985ec7fa 100644
--- a/tests/Composer/Test/Fixtures/installer/update-dev-to-new-ref-picks-up-changes.test
+++ b/tests/Composer/Test/Fixtures/installer/update-dev-to-new-ref-picks-up-changes.test
@@ -7,36 +7,39 @@ Updating a dev package to its latest ref should pick up new dependencies
             "type": "package",
             "package": [
                 {
-                    "name": "a/devpackage", "version": "dev-master",
+                    "name": "a/devpackage", "version": "dev-main",
                     "source": { "reference": "newref", "url": "", "type": "git" },
                     "require": {
                         "a/dependency": "*"
-                    }
+                    },
+                    "default-branch": true
                 },
                 {
-                    "name": "a/dependency", "version": "dev-master",
+                    "name": "a/dependency", "version": "dev-main",
                     "source": { "reference": "ref", "url": "", "type": "git" },
-                    "require": {}
+                    "require": {},
+                    "default-branch": true
                 }
             ]
         }
     ],
     "require": {
-        "a/devpackage": "dev-master"
+        "a/devpackage": "dev-main"
     },
     "minimum-stability": "dev"
 }
 --INSTALLED--
 [
     {
-        "name": "a/devpackage", "version": "dev-master",
+        "name": "a/devpackage", "version": "dev-main",
         "source": { "reference": "oldref", "url": "", "type": "git" },
-        "require": {}
+        "require": {},
+        "default-branch": true
     }
 ]
 --RUN--
 update
 --EXPECT--
-Installing a/dependency (dev-master ref)
-Marking a/dependency (9999999-dev ref) as installed, alias of a/dependency (dev-master ref)
-Upgrading a/devpackage (dev-master oldref => dev-master newref)
+Installing a/dependency (dev-main ref)
+Marking a/dependency (9999999-dev ref) as installed, alias of a/dependency (dev-main ref)
+Upgrading a/devpackage (dev-main oldref => dev-main newref)
diff --git a/tests/Composer/Test/Fixtures/installer/update-downgrades-unstable-packages.test b/tests/Composer/Test/Fixtures/installer/update-downgrades-unstable-packages.test
index b213e480d..7b0a87e59 100644
--- a/tests/Composer/Test/Fixtures/installer/update-downgrades-unstable-packages.test
+++ b/tests/Composer/Test/Fixtures/installer/update-downgrades-unstable-packages.test
@@ -8,7 +8,8 @@ Downgrading from unstable to more stable package should work even if already ins
             "package": [
                 {
                     "name": "a/a", "version": "dev-master",
-                    "source": { "reference": "abcd", "url": "", "type": "git" }
+                    "source": { "reference": "abcd", "url": "", "type": "git" },
+                    "default-branch": true
                 },
                 {
                     "name": "a/a", "version": "1.0.0",
@@ -17,7 +18,8 @@ Downgrading from unstable to more stable package should work even if already ins
                 },
                 {
                     "name": "b/b", "version": "dev-master",
-                    "source": { "reference": "abcd", "url": "", "type": "git" }
+                    "source": { "reference": "abcd", "url": "", "type": "git" },
+                    "default-branch": true
                 },
                 {
                     "name": "b/b", "version": "1.0.0",
@@ -36,11 +38,13 @@ Downgrading from unstable to more stable package should work even if already ins
 [
     {
         "name": "a/a", "version": "dev-master",
-        "source": { "reference": "abcd", "url": "", "type": "git" }
+        "source": { "reference": "abcd", "url": "", "type": "git" },
+        "default-branch": true
     },
     {
         "name": "b/b", "version": "dev-master",
-        "source": { "reference": "abcd", "url": "", "type": "git" }
+        "source": { "reference": "abcd", "url": "", "type": "git" },
+        "default-branch": true
     }
 ]
 --RUN--
diff --git a/tests/Composer/Test/Fixtures/installer/update-to-empty-from-locked.test b/tests/Composer/Test/Fixtures/installer/update-to-empty-from-locked.test
index 89e94d781..1a2227cec 100644
--- a/tests/Composer/Test/Fixtures/installer/update-to-empty-from-locked.test
+++ b/tests/Composer/Test/Fixtures/installer/update-to-empty-from-locked.test
@@ -8,7 +8,8 @@ Update to a state without dependency works well from locked with dependency
 [
     {
         "name": "a/a", "version": "dev-master",
-        "source": { "reference": "1234", "type": "git", "url": "" }
+        "source": { "reference": "1234", "type": "git", "url": "" },
+        "default-branch": true
     }
 ]
 --LOCK--
@@ -17,7 +18,8 @@ Update to a state without dependency works well from locked with dependency
         {
             "name": "a/a", "version": "dev-master",
             "source": { "reference": "1234", "type": "git", "url": "" },
-            "type": "library"
+            "type": "library",
+            "default-branch": true
         }
     ],
     "packages-dev": [],
diff --git a/tests/Composer/Test/Fixtures/installer/updating-dev-from-lock-removes-old-deps.test b/tests/Composer/Test/Fixtures/installer/updating-dev-from-lock-removes-old-deps.test
index ec92ea607..d5613a648 100644
--- a/tests/Composer/Test/Fixtures/installer/updating-dev-from-lock-removes-old-deps.test
+++ b/tests/Composer/Test/Fixtures/installer/updating-dev-from-lock-removes-old-deps.test
@@ -13,7 +13,8 @@ Installing locked dev packages should remove old dependencies
         {
             "name": "a/devpackage", "version": "dev-master",
             "source": { "reference": "newref", "url": "", "type": "git" },
-            "require": {}
+            "require": {},
+            "default-branch": true
         }
     ],
     "packages-dev": [],
@@ -30,12 +31,14 @@ Installing locked dev packages should remove old dependencies
         "source": { "reference": "oldref", "url": "", "type": "git" },
         "require": {
             "a/dependency": "*"
-        }
+        },
+        "default-branch": true
     },
     {
         "name": "a/dependency", "version": "dev-master",
         "source": { "reference": "ref", "url": "", "type": "git" },
-        "require": {}
+        "require": {},
+        "default-branch": true
     }
 ]
 --RUN--