Remove source-refs from lock file for alias packages

composer.lock

@@ -12,7 +12,6 @@
         {
             "package": "symfony/console",
             "version": "dev-master",
-            "source-reference": "1edd7b739561e87bde81ff1c2ce08bd89e92277e",
             "alias-pretty-version": "2.1.x-dev",
             "alias-version": "2.1.9999999.9999999-dev"
         },
@@ -24,7 +23,6 @@
         {
             "package": "symfony/finder",
             "version": "dev-master",
-            "source-reference": "a2cef64d5072b284b671ee8e06b8ebc38c2969e1",
             "alias-pretty-version": "2.1.x-dev",
             "alias-version": "2.1.9999999.9999999-dev"
         },
@@ -36,7 +34,6 @@
         {
             "package": "symfony/process",
             "version": "dev-master",
-            "source-reference": "106f2db51cecf2fe5ee59e428b8f4a918c4034fa",
             "alias-pretty-version": "2.1.x-dev",
             "alias-version": "2.1.9999999.9999999-dev"
         },

src/Composer/Package/Locker.php

@@ -221,7 +221,7 @@ class Locker
 
             $spec = array('package' => $name, 'version' => $version);
 
-            if ($package->isDev()) {
+            if ($package->isDev() && !$alias) {
                 $spec['source-reference'] = $package->getSourceReference();
             }