Fix whitespaces and add strict return code checking

src/Composer/Repository/Vcs/HgDriver.php

@@ -181,6 +181,6 @@ class HgDriver implements VcsDriverInterface
         }
 
         exec(sprintf('hg identify %s', escapeshellarg($url)), $ignored, $exit);
-        return $exit == 0;
+        return $exit === 0;
     }
 }

src/Composer/Repository/Vcs/SvnDriver.php

@@ -179,6 +179,6 @@ class SvnDriver implements VcsDriverInterface
         }
 
         exec(sprintf('svn info --non-interactive %s 2>/dev/null', escapeshellarg($url)), $ignored, $exit);
-        return $exit == 0;
+        return $exit === 0;
     }
 }