rebaseline-cl: trigger all try jobs in one invocation of git cl try.

third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_cl.py

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """A command to fetch new baselines from try jobs for a Rietveld issue.
 
 This command interacts with the Rietveld API to get information about try jobs
 with layout test results.
 """
 
@@ skipping 114 matching lines @@
         builders_without_builds = set(self._try_bots()) - builders_with_builds
         builders_with_pending_builds = {b.builder_name for b in builds if b.build_number is None}
 
         if builders_with_pending_builds:
             _log.info('There are existing pending builds for:')
             for builder in sorted(builders_with_pending_builds):
                 _log.info('  %s', builder)
 
         if builders_without_builds:
             _log.info('Triggering try jobs for:')
+            command = ['try']
             for builder in sorted(builders_without_builds):
                 _log.info('  %s', builder)
-            # If the builders may be under different masters, then they cannot
-            # all be started in one invocation of git cl try without providing
-            # master names. Doing separate invocations is slower, but always works
-            # even when there are builders under different master names.
-            for builder in sorted(builders_without_builds):
-                self.git_cl().run(['try', '-b', builder])
+                command.extend(['-b', builder])
+            self.git_cl().run(command)
 
         return bool(builders_with_pending_builds or builders_without_builds)
 
     def _test_prefix_list(self, issue_number, only_changed_tests):
         """Returns a collection of test, builder and file extensions to get new baselines for.
 
         Args:
             issue_number: The CL number of the change which needs new baselines.
             only_changed_tests: Whether to only include baselines for tests that
                are changed in this CL. If False, all new baselines for failing
@@ skipping 44 matching lines @@
     @staticmethod
     def _log_test_prefix_list(test_prefix_list):
         """Logs the tests to download new baselines for."""
         if not test_prefix_list:
             _log.info('No tests to rebaseline; exiting.')
             return
         _log.info('Tests to rebaseline:')
         for test, builds in test_prefix_list.iteritems():
             builds_str = ', '.join(sorted('%s (%s)' % (b.builder_name, b.build_number) for b in builds))
             _log.info('  %s: %s', test, builds_str)