Bug 1406777 - Support --message and --no-push with |mach try empty|, r=armenzg

This adds all the common arguments to |mach try empty|, including preset
arguments which will just be ignored if specified. The commit message can be
changed with:
./mach try empty -m DONTBUILD

MozReview-Commit-ID: 5RYfLBOIX1g

--HG--
extra : rebase_source : 412cbc50c2901a97893779a73a7f70d5ee6e2d72

tools/tryselect/mach_commands.py

@@ -38,9 +38,13 @@ def fuzzy_parser():
     return FuzzyParser()
 
 
-def generic_parser():
+def base_parser():
     from tryselect.cli import BaseTryParser
-    parser = BaseTryParser()
+    return BaseTryParser()
+
+
+def generic_parser():
+    parser = base_parser()
     parser.add_argument('argv', nargs=argparse.REMAINDER)
     return parser
 
@@ -144,8 +148,9 @@ class TrySelect(MachCommandBase):
 
     @SubCommand('try',
                 'empty',
-                description='Push to try without scheduling any tasks.')
-    def try_empty(self):
+                description='Push to try without scheduling any tasks.',
+                parser=base_parser)
+    def try_empty(self, **kwargs):
         """Push to try, running no builds or tests
 
         This selector does not prompt you to run anything, it just pushes
@@ -155,7 +160,7 @@ class TrySelect(MachCommandBase):
         menu.
         """
         from tryselect.selectors.empty import run_empty_try
-        return run_empty_try()
+        return run_empty_try(**kwargs)
 
     @SubCommand('try',
                 'syntax',

tools/tryselect/selectors/empty.py

@@ -7,6 +7,7 @@ from __future__ import absolute_import, print_function, unicode_literals
 from ..vcs import VCSHelper
 
 
-def run_empty_try():
+def run_empty_try(message='{msg}', push=True, **kwargs):
     vcs = VCSHelper.create()
-    return vcs.push_to_try("empty", "", [])
+    msg = 'No try selector specified, use "Add New Jobs" to select tasks.'
+    return vcs.push_to_try('empty', message.format(msg=msg), [], push=push)