[blinkpy update_expectations] Don't repeat bug numbers

When update_expectations.py is run, it outputs a suggested CL
description, including bug numbers.  This CL changes the output
to stop repeating bug numbers.

Change-Id: Iabe10680f07b28832e7336ceb2105a1db03eaa80
Reviewed-on: https://chromium-review.googlesource.com/1089293
Commit-Queue: Quinten Yearsley <qyearsley@chromium.org>
Reviewed-by: David Bokan <bokan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565751}

third_party/blink/tools/blinkpy/web_tests/update_expectations.py

@@ -48,8 +48,7 @@ def main(host, bot_test_expectations_factory, argv):
                         default='all',
                         help='type of expectations to update (default: %(default)s)')
     parser.add_argument('--verbose', '-v', action='store_true', default=False, help='enable more verbose logging')
-    parser.add_argument('--show-results',
-                        '-s',
+    parser.add_argument('--show-results', '-s',
                         action='store_true',
                         default=False,
                         help='Open results dashboard for all removed lines')
@@ -388,9 +387,9 @@ class ExpectationsRemover(object):
 
     def _bug_numbers(self):
         """Returns the list of all bug numbers affected by this change."""
-        numbers = []
+        numbers = set()
         for line in self._expectations_to_remove():
             for bug in line.bugs:
                 if bug.startswith(CHROMIUM_BUG_PREFIX):
-                    numbers.append(bug[len(CHROMIUM_BUG_PREFIX):])
+                    numbers.add(bug[len(CHROMIUM_BUG_PREFIX):])
         return sorted(numbers)

third_party/blink/tools/blinkpy/web_tests/update_expectations_unittest.py

@@ -1411,13 +1411,13 @@ class UpdateTestExpectationsTest(LoggingTestCase):
         """
         test_expectations_before = (
             """# Remove this since it's passing all runs.
-            crbug.com/2222 test/a.html [ Failure Pass ]
+            crbug.com/1111 test/a.html [ Failure Pass ]
             # Remove this since, although there's a failure, it's not a timeout.
             crbug.com/1111 test/b.html [ Pass Timeout ]
             # Keep since we have both crashes and passes.
-            crbug.com/3333 test/c.html [ Crash Pass ]
+            crbug.com/2222 test/c.html [ Crash Pass ]
             # Remove since it's passing all runs.
-            crbug.com/4444 test/d.html [ Failure ]""")
+            crbug.com/3333 test/d.html [ Failure ]""")
 
         self._expectations_remover = self._create_expectations_remover()
         self._define_builders({
@@ -1440,14 +1440,14 @@ class UpdateTestExpectationsTest(LoggingTestCase):
         }
         self._expectations_remover.print_suggested_commit_description()
         self.assertLog([
-            'INFO: Deleting line "crbug.com/2222 test/a.html [ Failure Pass ]"\n',
+            'INFO: Deleting line "crbug.com/1111 test/a.html [ Failure Pass ]"\n',
             'INFO: Deleting line "crbug.com/1111 test/b.html [ Pass Timeout ]"\n',
-            'INFO: Deleting line "crbug.com/4444 test/d.html [ Failure ]"\n',
+            'INFO: Deleting line "crbug.com/3333 test/d.html [ Failure ]"\n',
             'INFO: Suggested commit description:\n'
             'Remove TestExpectations which are not failing in the specified way.\n\n'
             'This change was made by the update_expectations.py script.\n\n'
             'Recent test results history:\n'
             'https://test-results.appspot.com/dashboards/flakiness_dashboard.html'
             '#testType=webkit_layout_tests&tests=test/a.html,test/b.html,test/d.html\n\n'
-            'Bug: 1111, 2222, 4444\n'
+            'Bug: 1111, 3333\n'
         ])