Fix argument checking in gcl.py

gcl.py

Index: gcl.py
diff --git a/gcl.py b/gcl.py
index 66c3389f6acf2e37e02afc6e71d4977a3480bb01..c8756e14bb41297e8047705be256eb64e61294da 100755
--- a/gcl.py
+++ b/gcl.py
@@ -667,6 +667,8 @@ def need_change(function):
 def need_change_and_args(function):
   """Converts args -> change_info."""
   def hook(args):
+    if not args:
+      ErrorExit("You need to pass a change list name")
     change_info = ChangeInfo.Load(args.pop(0), GetRepositoryRoot(), True, True)
     return function(change_info, args)
   defer_attributes(function, hook)