git cl try: Simplify _get_bucket_map.

git_cl.py

Index: git_cl.py
diff --git a/git_cl.py b/git_cl.py
index 6b0d304913564e07865e76fdb768534aa41c36df..dd538237443390d60a9f15661e82c6bdbbdee893 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -341,14 +341,15 @@ def _buildbucket_retry(operation_name, http, *args, **kwargs):
 
 
 def _get_bucket_map(changelist, options, option_parser):
-  """Returns a dict mapping bucket names (or master names) to
-  builders and tests, for triggering try jobs.
+  """Returns a dict mapping bucket names to builders and tests,

[qyearsley, 2016/10/27 20:36:06]

This could potentially be simplified further to not support listing tests for
each builder. 

This might potentially change behavior though, since
presubmit_support.DoGetTryMasters could return a dict mapping masters to
builders to tests, and in order to not support listing tests, we would change
this to just ignore the tests returned from any GetPreferredTryMasters
functions. Does this sound like something you'd like to do?

[tandrii(chromium), 2016/10/28 15:42:04]

Ideally, yes, but there is always a possibility of breaking somebody :(
I've caused too many breakages this year with git cl and my plate is full now. 
I will support you if you want to do it.

+  for triggering try jobs.
   """
+  # If no bots are listed, we try to get a set of builders and tests based
+  # on GetPreferredTryMasters functions in PRESUBMIT.py files.
   if not options.bot:
     change = changelist.GetChange(
         changelist.GetCommonAncestorWithUpstream(), None)
 
-    # Get try masters from PRESUBMIT.py files.
     masters = presubmit_support.DoGetTryMasters(
         change=change,
         changed_files=change.LocalPaths(),
@@ -376,42 +377,22 @@ def _get_bucket_map(changelist, options, option_parser):
     if not options.bot:
       return {}
 
+  # If a bucket or master is passed, then we assume all bots are under
+  # that one master.
   if options.bucket:
     return {options.bucket: {b: [] for b in options.bot}}
+  if options.master:
+    return {_prefix_master(options.master): {b: [] for b in options.bot}}
 
-  if not options.master:
-    bucket_map, error_message = _get_bucket_map_for_builders(options.bot)
-    if error_message:
-      option_parser.error(
-          'Tryserver master cannot be found because: %s\n'
-          'Please manually specify the tryserver master, e.g. '
-          '"-m tryserver.chromium.linux".' % error_message)
-    return bucket_map
-
-  builders_and_tests = {}
-
-  # TODO(machenbach): The old style command-line options don't support
-  # multiple try masters yet.
-  # TODO(qyearsley): If options.bot is always a list of strings, then
-  # "new_style" never applies, and so we should remove support for Specifying
-  # test filters completely.
-  old_style = filter(lambda x: isinstance(x, basestring), options.bot)
-  new_style = filter(lambda x: isinstance(x, tuple), options.bot)
-
-  for bot in old_style:
-    if ':' in bot:
-      option_parser.error('Specifying testfilter is no longer supported')
-    elif ',' in bot:
-      option_parser.error('Specify one bot per --bot flag')
-    else:
-      builders_and_tests.setdefault(bot, [])
-
-  for bot, tests in new_style:
-    builders_and_tests.setdefault(bot, []).extend(tests)
-
-  # Add the "master." prefix to the master name to obtain the bucket name.
-  bucket = _prefix_master(options.master)
-  return {bucket: builders_and_tests}
+  # If bots are listed but no master or bucket, then we need to find out
+  # the corresponding master for each bot.
+  bucket_map, error_message = _get_bucket_map_for_builders(options.bot)
+  if error_message:
+    option_parser.error(
+        'Tryserver master cannot be found because: %s\n'
+        'Please manually specify the tryserver master, e.g. '
+        '"-m tryserver.chromium.linux".' % error_message)
+  return bucket_map
 
 
 def _get_bucket_map_for_builders(builders):
@@ -429,7 +410,6 @@ def _get_bucket_map_for_builders(builders):
 
   bucket_map = {}
   for builder in builders:
-    builder = builder.split(':', 1)[0]
     masters = builders_map.get(builder, [])
     if not masters:
       return None, ('No matching master for builder %s.' % builder)
@@ -4870,8 +4850,9 @@ def CMDtry(parser, args):
 
   buckets = _get_bucket_map(cl, options, parser)
 
+  # If no bots are listed and we couldn't get a list based on PRESUBMIT files,
+  # then we default to triggering a dry run (see http://crbug.com/625697).

[tandrii(chromium), 2016/10/28 15:42:04]

s/a dry run/a CQ dry run

   if not buckets:
-    # Default to triggering Dry Run (see http://crbug.com/625697).
     if options.verbose:
       print('git cl try with no bots now defaults to CQ Dry Run.')
     return cl.TriggerDryRun()