Add a --ignore-self parameter to "git cl owners"

Sometimes CL author is also listed as OWNERS but want to find a co-owner
to review CL. Currently "git cl owners" is unhelpful as it consider the
author's ownership as enough.

Add a --ignore-self parameter to "git cl owners" that will cause the
tool to ignore author's ownership when looking for a reviewer.

Bug: none
Change-Id: Iba110a465a552cd6befb46c77b2e65f60b663a13
Reviewed-on: https://chromium-review.googlesource.com/c/1459625
Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>

git_cl.py

@@ -5098,6 +5098,10 @@ def CMDowners(parser, args):
       '--ignore-current',
       action='store_true',
       help='Ignore the CL\'s current reviewers and start from scratch.')
+  parser.add_option(
+      '--ignore-self',
+      action='store_true',
+      help='Do not consider CL\'s author as an owners.')
   parser.add_option(
       '--no-color',
       action='store_true',
@@ -5137,7 +5141,8 @@ def CMDowners(parser, args):
       [] if options.ignore_current else cl.GetReviewers(),
       fopen=file, os_path=os.path,
       disable_color=options.no_color,
-      override_files=change.OriginalOwnersFiles()).run()
+      override_files=change.OriginalOwnersFiles(),
+      ignore_author=options.ignore_self).run()
 
 
 def BuildGitDiffCmd(diff_type, upstream_commit, args, allow_prefix=False):

owners_finder.py

@@ -26,7 +26,8 @@ class OwnersFinder(object):
                fopen, os_path,
                email_postfix='@chromium.org',
                disable_color=False,
-               override_files=None):
+               override_files=None,
+               ignore_author=False):
     self.email_postfix = email_postfix
 
     if os.name == 'nt' or disable_color:
@@ -46,7 +47,7 @@ class OwnersFinder(object):
     filtered_files = files
 
     reviewers = list(reviewers)
-    if author:
+    if author and not ignore_author:
       reviewers.append(author)
 
     # Eliminate files that existing reviewers can review.
@@ -62,6 +63,8 @@ class OwnersFinder(object):
       self.db.load_data_needed_for(files)
 
     self.all_possible_owners = self.db.all_possible_owners(files, None)
+    if author and author in self.all_possible_owners:
+      del self.all_possible_owners[author]
 
     self.owners_to_files = {}
     self._map_owners_to_files(files)