[git-cl-try] handle -m luci.foo.bar

If -m option value starts with "luci.", most probably the user intends
to schedule a build on a LUCI bucket. Print an error message asking
the user to use -B option.

Bug: 749696
Change-Id: If7a038a1f629ee808e3261ae1c753e388bfea893
Reviewed-on: https://chromium-review.googlesource.com/707534
Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Nodir Turakulov <nodir@chromium.org>

git_cl.py

@@ -5478,7 +5478,7 @@ def CMDtry(parser, args):
       help=('Buildbucket bucket to send the try requests.'))
   group.add_option(
       '-m', '--master', default='',
-      help=('Specify a try master where to run the tries.'))
+      help=('DEPRECATED, use -B. The try master where to run the builds.'))
   group.add_option(
       '-r', '--revision',
       help='Revision to use for the try job; default: the revision will '
@@ -5508,6 +5508,9 @@ def CMDtry(parser, args):
   options, args = parser.parse_args(args)
   auth_config = auth.extract_auth_config_from_options(options)
 
+  if options.master and options.master.startswith('luci.'):
+    parser.error(
+        '-m option does not support LUCI. Please pass -B %s' % options.master)
   # Make sure that all properties are prop=value pairs.
   bad_params = [x for x in options.properties if '=' not in x]
   if bad_params: