Fix up arg parsing.

Using parser as a var screwed up the arg parsing and added every
command's arg which would then complain about required args missing when
the command wasn't even specified.

Bug: None
Test: acloud doesn't complain about required args unrelated to cmd.
Change-Id: Ibe2dbfce78fb9a167edb7096a8380eb907af6332
diff --git a/public/acloud_main.py b/public/acloud_main.py
index 403a0af..9ff0168 100644
--- a/public/acloud_main.py
+++ b/public/acloud_main.py
@@ -367,8 +367,8 @@
     subparser_list.append(sshkey_parser)
 
     # Add common arguments.
-    for parser in subparser_list:
-        acloud_common.AddCommonArguments(parser)
+    for subparser in subparser_list:
+        acloud_common.AddCommonArguments(subparser)
 
     return parser.parse_args(args)