Do not allow credentials files to be symlinks.
Reviewed in https://codereview.appspot.com/6476062/.
diff --git a/oauth2client/multistore_file.py b/oauth2client/multistore_file.py
index e190c6a..c919573 100644
--- a/oauth2client/multistore_file.py
+++ b/oauth2client/multistore_file.py
@@ -76,7 +76,7 @@
     An object derived from client.Storage for getting/setting the
     credential.
   """
-  filename = os.path.realpath(os.path.expanduser(filename))
+  filename = os.path.expanduser(filename)
   _multistores_lock.acquire()
   try:
     multistore = _multistores.setdefault(