diff --git a/src/Composer/Downloader/GitDownloader.php b/src/Composer/Downloader/GitDownloader.php
index 9d8e53070..22baff7fd 100644
--- a/src/Composer/Downloader/GitDownloader.php
+++ b/src/Composer/Downloader/GitDownloader.php
@@ -35,7 +35,7 @@ class GitDownloader extends VcsDownloader
         $this->runCommand($commandCallable, $package->getSourceUrl(), $path);
         $this->setPushUrl($package, $path);
 
-        $this->updateToCommit($path, $ref, $package->getPrettyVersion(), $package->getReleaseDate()->format('U'));
+        $this->updateToCommit($path, $ref, $package->getPrettyVersion(), $package->getReleaseDate());
     }
 
     /**
@@ -58,7 +58,7 @@ class GitDownloader extends VcsDownloader
         };
 
         $this->runCommand($commandCallable, $target->getSourceUrl());
-        $this->updateToCommit($path, $ref, $target->getPrettyVersion(), $target->getReleaseDate()->format('U'));
+        $this->updateToCommit($path, $ref, $target->getPrettyVersion(), $target->getReleaseDate());
     }
 
     protected function updateToCommit($path, $reference, $branch, $date)
@@ -71,8 +71,9 @@ class GitDownloader extends VcsDownloader
         }
 
         // reference was not found (prints "fatal: reference is not a tree: $ref")
-        if (false !== strpos($this->process->getErrorOutput(), $reference)) {
+        if ($date && false !== strpos($this->process->getErrorOutput(), $reference)) {
             $branch = preg_replace('{(?:^dev-|(?:\.x)?-dev$)}i', '', $branch);
+            $date = $date->format('U');
 
             $command = 'git branch -r';
             if (1 === $this->process->execute($command, $output, $path)) {
diff --git a/src/Composer/Package/Locker.php b/src/Composer/Package/Locker.php
index a619c45e6..1f64209a8 100644
--- a/src/Composer/Package/Locker.php
+++ b/src/Composer/Package/Locker.php
@@ -223,8 +223,7 @@ class Locker
 
             if ($package->isDev() && !$alias) {
                 $spec['source-reference'] = $package->getSourceReference();
-                if ('git' === $package->getSourceType()) {
-                    $path = $this->installationManager->getInstallPath($package);
+                if ('git' === $package->getSourceType() && $path = $this->installationManager->getInstallPath($package)) {
                     $process = new ProcessExecutor();
                     if (0 === $process->execute('git log -n1 --pretty=%ct '.escapeshellarg($package->getSourceReference()), $output, $path)) {
                         $spec['commit-date'] = trim($output);
diff --git a/tests/Composer/Test/Downloader/GitDownloaderTest.php b/tests/Composer/Test/Downloader/GitDownloaderTest.php
index 81a7172e3..639913498 100644
--- a/tests/Composer/Test/Downloader/GitDownloaderTest.php
+++ b/tests/Composer/Test/Downloader/GitDownloaderTest.php
@@ -50,12 +50,17 @@ class GitDownloaderTest extends \PHPUnit_Framework_TestCase
             ->will($this->returnValue('https://example.com/composer/composer'));
         $processExecutor = $this->getMock('Composer\Util\ProcessExecutor');
 
-        $expectedGitCommand = $this->getCmd("git clone 'https://example.com/composer/composer' 'composerPath' && cd 'composerPath' && git checkout 'ref' && git reset --hard 'ref' && git remote add composer 'https://example.com/composer/composer'");
-        $processExecutor->expects($this->once())
+        $expectedGitCommand = $this->getCmd("git clone 'https://example.com/composer/composer' 'composerPath' && cd 'composerPath' && git remote add composer 'https://example.com/composer/composer' && git fetch composer");
+        $processExecutor->expects($this->at(0))
             ->method('execute')
             ->with($this->equalTo($expectedGitCommand))
             ->will($this->returnValue(0));
 
+        $processExecutor->expects($this->at(1))
+            ->method('execute')
+            ->with($this->equalTo($this->getCmd("git checkout 'ref' && git reset --hard 'ref'")), $this->equalTo(null), $this->equalTo('composerPath'))
+            ->will($this->returnValue(0));
+
         $downloader = $this->getDownloaderMock(null, $processExecutor);
         $downloader->download($packageMock, 'composerPath');
     }
@@ -71,19 +76,19 @@ class GitDownloaderTest extends \PHPUnit_Framework_TestCase
             ->will($this->returnValue('https://github.com/composer/composer'));
         $processExecutor = $this->getMock('Composer\Util\ProcessExecutor');
 
-        $expectedGitCommand = $this->getCmd("git clone 'git://github.com/composer/composer' 'composerPath' && cd 'composerPath' && git checkout 'ref' && git reset --hard 'ref' && git remote add composer 'git://github.com/composer/composer'");
+        $expectedGitCommand = $this->getCmd("git clone 'git://github.com/composer/composer' 'composerPath' && cd 'composerPath' && git remote add composer 'git://github.com/composer/composer' && git fetch composer");
         $processExecutor->expects($this->at(0))
             ->method('execute')
             ->with($this->equalTo($expectedGitCommand))
             ->will($this->returnValue(1));
 
-        $expectedGitCommand = $this->getCmd("git clone 'https://github.com/composer/composer' 'composerPath' && cd 'composerPath' && git checkout 'ref' && git reset --hard 'ref' && git remote add composer 'https://github.com/composer/composer'");
+        $expectedGitCommand = $this->getCmd("git clone 'https://github.com/composer/composer' 'composerPath' && cd 'composerPath' && git remote add composer 'https://github.com/composer/composer' && git fetch composer");
         $processExecutor->expects($this->at(2))
             ->method('execute')
             ->with($this->equalTo($expectedGitCommand))
             ->will($this->returnValue(1));
 
-        $expectedGitCommand = $this->getCmd("git clone 'http://github.com/composer/composer' 'composerPath' && cd 'composerPath' && git checkout 'ref' && git reset --hard 'ref' && git remote add composer 'http://github.com/composer/composer'");
+        $expectedGitCommand = $this->getCmd("git clone 'http://github.com/composer/composer' 'composerPath' && cd 'composerPath' && git remote add composer 'http://github.com/composer/composer' && git fetch composer");
         $processExecutor->expects($this->at(4))
             ->method('execute')
             ->with($this->equalTo($expectedGitCommand))
@@ -95,6 +100,11 @@ class GitDownloaderTest extends \PHPUnit_Framework_TestCase
             ->with($this->equalTo($expectedGitCommand), $this->equalTo(null), $this->equalTo('composerPath'))
             ->will($this->returnValue(0));
 
+        $processExecutor->expects($this->at(6))
+            ->method('execute')
+            ->with($this->equalTo($this->getCmd("git checkout 'ref' && git reset --hard 'ref'")), $this->equalTo(null), $this->equalTo('composerPath'))
+            ->will($this->returnValue(0));
+
         $downloader = $this->getDownloaderMock(null, $processExecutor);
         $downloader->download($packageMock, 'composerPath');
     }
@@ -104,7 +114,7 @@ class GitDownloaderTest extends \PHPUnit_Framework_TestCase
      */
     public function testDownloadThrowsRuntimeExceptionIfGitCommandFails()
     {
-        $expectedGitCommand = $this->getCmd("git clone 'https://example.com/composer/composer' 'composerPath' && cd 'composerPath' && git checkout 'ref' && git reset --hard 'ref' && git remote add composer 'https://example.com/composer/composer'");
+        $expectedGitCommand = $this->getCmd("git clone 'https://example.com/composer/composer' 'composerPath' && cd 'composerPath' && git remote add composer 'https://example.com/composer/composer' && git fetch composer");
         $packageMock = $this->getMock('Composer\Package\PackageInterface');
         $packageMock->expects($this->any())
             ->method('getSourceReference')
@@ -139,7 +149,7 @@ class GitDownloaderTest extends \PHPUnit_Framework_TestCase
 
     public function testUpdate()
     {
-        $expectedGitUpdateCommand = $this->getCmd("cd 'composerPath' && git remote set-url composer 'git://github.com/composer/composer' && git fetch composer && git fetch --tags composer && git checkout 'ref' && git reset --hard 'ref'");
+        $expectedGitUpdateCommand = $this->getCmd("cd 'composerPath' && git remote set-url composer 'git://github.com/composer/composer' && git fetch composer && git fetch --tags composer");
         $expectedGitResetCommand = $this->getCmd("cd 'composerPath' && git status --porcelain --untracked-files=no");
 
         $packageMock = $this->getMock('Composer\Package\PackageInterface');
@@ -162,6 +172,10 @@ class GitDownloaderTest extends \PHPUnit_Framework_TestCase
             ->method('execute')
             ->with($this->equalTo($expectedGitUpdateCommand))
             ->will($this->returnValue(0));
+        $processExecutor->expects($this->at(3))
+            ->method('execute')
+            ->with($this->equalTo($this->getCmd("git checkout 'ref' && git reset --hard 'ref'")), $this->equalTo(null), $this->equalTo('composerPath'))
+            ->will($this->returnValue(0));
 
         $downloader = $this->getDownloaderMock(null, $processExecutor);
         $downloader->update($packageMock, $packageMock, 'composerPath');
@@ -172,7 +186,7 @@ class GitDownloaderTest extends \PHPUnit_Framework_TestCase
      */
     public function testUpdateThrowsRuntimeExceptionIfGitCommandFails()
     {
-        $expectedGitUpdateCommand = $this->getCmd("cd 'composerPath' && git remote set-url composer 'git://github.com/composer/composer' && git fetch composer && git fetch --tags composer && git checkout 'ref' && git reset --hard 'ref'");
+        $expectedGitUpdateCommand = $this->getCmd("cd 'composerPath' && git remote set-url composer 'git://github.com/composer/composer' && git fetch composer && git fetch --tags composer");
         $expectedGitResetCommand = $this->getCmd("cd 'composerPath' && git status --porcelain --untracked-files=no");
 
         $packageMock = $this->getMock('Composer\Package\PackageInterface');
diff --git a/tests/Composer/Test/InstallerTest.php b/tests/Composer/Test/InstallerTest.php
index 8361af192..0dfff7b0b 100644
--- a/tests/Composer/Test/InstallerTest.php
+++ b/tests/Composer/Test/InstallerTest.php
@@ -170,7 +170,7 @@ class InstallerTest extends TestCase
             ->method('exists')
             ->will($this->returnValue(true));
 
-        $locker = new Locker($lockJsonMock, $repositoryManager, md5(json_encode($composerConfig)));
+        $locker = new Locker($lockJsonMock, $repositoryManager, $composer->getInstallationManager(), md5(json_encode($composerConfig)));
         $composer->setLocker($locker);
 
         $autoloadGenerator = $this->getMock('Composer\Autoload\AutoloadGenerator');
diff --git a/tests/Composer/Test/Mock/InstallationManagerMock.php b/tests/Composer/Test/Mock/InstallationManagerMock.php
index cc587a6f9..4bccc63f8 100644
--- a/tests/Composer/Test/Mock/InstallationManagerMock.php
+++ b/tests/Composer/Test/Mock/InstallationManagerMock.php
@@ -13,6 +13,7 @@ namespace Composer\Test\Mock;
 
 use Composer\Installer\InstallationManager;
 use Composer\Repository\RepositoryInterface;
+use Composer\Package\PackageInterface;
 use Composer\DependencyResolver\Operation\InstallOperation;
 use Composer\DependencyResolver\Operation\UpdateOperation;
 use Composer\DependencyResolver\Operation\UninstallOperation;
@@ -26,6 +27,11 @@ class InstallationManagerMock extends InstallationManager
     private $uninstalled = array();
     private $trace = array();
 
+    public function getInstallPath(PackageInterface $package)
+    {
+        return '';
+    }
+
     public function install(RepositoryInterface $repo, InstallOperation $operation)
     {
         $this->installed[] = $operation->getPackage();
diff --git a/tests/Composer/Test/Package/LockerTest.php b/tests/Composer/Test/Package/LockerTest.php
index a67beb277..2f93d77e2 100644
--- a/tests/Composer/Test/Package/LockerTest.php
+++ b/tests/Composer/Test/Package/LockerTest.php
@@ -19,7 +19,7 @@ class LockerTest extends \PHPUnit_Framework_TestCase
     public function testIsLocked()
     {
         $json   = $this->createJsonFileMock();
-        $locker = new Locker($json, $this->createRepositoryManagerMock(), 'md5');
+        $locker = new Locker($json, $this->createRepositoryManagerMock(), $this->createInstallationManagerMock(), 'md5');
 
         $json
             ->expects($this->any())
@@ -37,8 +37,9 @@ class LockerTest extends \PHPUnit_Framework_TestCase
     {
         $json = $this->createJsonFileMock();
         $repo = $this->createRepositoryManagerMock();
+        $inst = $this->createInstallationManagerMock();
 
-        $locker = new Locker($json, $repo, 'md5');
+        $locker = new Locker($json, $repo, $inst, 'md5');
 
         $json
             ->expects($this->once())
@@ -54,8 +55,9 @@ class LockerTest extends \PHPUnit_Framework_TestCase
     {
         $json = $this->createJsonFileMock();
         $repo = $this->createRepositoryManagerMock();
+        $inst = $this->createInstallationManagerMock();
 
-        $locker = new Locker($json, $repo, 'md5');
+        $locker = new Locker($json, $repo, $inst, 'md5');
 
         $json
             ->expects($this->once())
@@ -87,8 +89,9 @@ class LockerTest extends \PHPUnit_Framework_TestCase
     {
         $json = $this->createJsonFileMock();
         $repo = $this->createRepositoryManagerMock();
+        $inst = $this->createInstallationManagerMock();
 
-        $locker = new Locker($json, $repo, 'md5');
+        $locker = new Locker($json, $repo, $inst, 'md5');
 
         $json
             ->expects($this->once())
@@ -122,8 +125,9 @@ class LockerTest extends \PHPUnit_Framework_TestCase
     {
         $json = $this->createJsonFileMock();
         $repo = $this->createRepositoryManagerMock();
+        $inst = $this->createInstallationManagerMock();
 
-        $locker = new Locker($json, $repo, 'md5');
+        $locker = new Locker($json, $repo, $inst, 'md5');
 
         $package1 = $this->createPackageMock();
         $package2 = $this->createPackageMock();
@@ -168,8 +172,9 @@ class LockerTest extends \PHPUnit_Framework_TestCase
     {
         $json = $this->createJsonFileMock();
         $repo = $this->createRepositoryManagerMock();
+        $inst = $this->createInstallationManagerMock();
 
-        $locker = new Locker($json, $repo, 'md5');
+        $locker = new Locker($json, $repo, $inst, 'md5');
 
         $package1 = $this->createPackageMock();
         $package1
@@ -186,8 +191,9 @@ class LockerTest extends \PHPUnit_Framework_TestCase
     {
         $json = $this->createJsonFileMock();
         $repo = $this->createRepositoryManagerMock();
+        $inst = $this->createInstallationManagerMock();
 
-        $locker = new Locker($json, $repo, 'md5');
+        $locker = new Locker($json, $repo, $inst, 'md5');
 
         $json
             ->expects($this->once())
@@ -201,8 +207,9 @@ class LockerTest extends \PHPUnit_Framework_TestCase
     {
         $json = $this->createJsonFileMock();
         $repo = $this->createRepositoryManagerMock();
+        $inst = $this->createInstallationManagerMock();
 
-        $locker = new Locker($json, $repo, 'md5');
+        $locker = new Locker($json, $repo, $inst, 'md5');
 
         $json
             ->expects($this->once())
@@ -232,6 +239,15 @@ class LockerTest extends \PHPUnit_Framework_TestCase
         return $mock;
     }
 
+    private function createInstallationManagerMock()
+    {
+        $mock = $this->getMockBuilder('Composer\Installer\InstallationManager')
+            ->disableOriginalConstructor()
+            ->getMock();
+
+        return $mock;
+    }
+
     private function createPackageMock()
     {
         return $this->getMockBuilder('Composer\Package\PackageInterface')