Add a safeguard because I always use -p 8000 by error when I mean --port 8000.

R=dpranke@chromium.org
BUG=
TEST=


Review URL: http://codereview.chromium.org/8261001

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@105226 0039d316-1c4b-4281-b951-d872f2087c98

trychange.py

@@ -656,6 +656,11 @@ def TryChange(argv,
 
   logging.debug(argv)
 
+  if (options.patchlevel is not None and
+      (options.patchlevel < 0 or options.patchlevel > 10)):
+    parser.error(
+        'Have you tried --port instead? You probably confused -p and -P.')
+
   # Strip off any @ in the user, otherwise svn gets confused.
   options.user = options.user.split('@', 1)[0]