Fix unixy proxy under git-bash

src/Composer/Installer/LibraryInstaller.php

@@ -201,7 +201,7 @@ class LibraryInstaller implements InstallerInterface
 
         return "#!/usr/bin/env sh\n".
             'SRC_DIR=`pwd`'."\n".
-            'cd `dirname \\`readlink -m "$0"\\``'."\n".
+            'cd `dirname "$0"`'."\n".
             'cd '.escapeshellarg(dirname($binPath))."\n".
             'BIN_TARGET=`pwd`/'.basename($binPath)."\n".
             'cd $SRC_DIR'."\n".