In rebaseline-cl, trigger try jobs with builder per invocation of git cl try.

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

Index: third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_cl.py
diff --git a/third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_cl.py b/third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_cl.py
index 707228361b2dabaf084799262f7129621e7aa906..f5ddd35ac2119f9fa0234906142157f22882b253 100644
--- a/third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_cl.py
+++ b/third_party/WebKit/Tools/Scripts/webkitpy/tool/commands/rebaseline_cl.py
@@ -97,11 +97,13 @@ class RebaselineCL(AbstractParallelRebaselineCommand):
         if not builders_without_builds:
             return
         _log.info('Triggering try jobs for: %s', ', '.join(sorted(builders_without_builds)))
+        # 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.
         git_cl = GitCL(self._tool.executive)
-        command = ['try']
         for builder in sorted(builders_without_builds):
-            command += ['-b', builder]
-        git_cl.run(command)
+            _log.info(git_cl.run(['try', '-b', builder]))

[wkorman, 2016/08/23 23:30:46]

remove log wrapper, looks like debugging?

[qyearsley, 2016/08/24 18:17:44]

I originally intended for this to provide more output to the user about what git
cl try is doing.

Although the list of builders that jobs are triggered for is already printed
above, and it's a good idea to not print more than required and not print
redundant information. So, I removed that in the latest patchset.

 
     def _test_prefix_list(self, issue_number, only_changed_tests):
         """Returns a collection of test, builder and file extensions to get new baselines for.