Produce blamelist pins in a consistent order.

The blamelist pins are produced by iterating over a dictionary which
yields a different order between python2 and python3. The blamelist pins
will now be produced with a consistent ordering between python versions
by sorting on the revision name.

Change-Id: Ieb6c4dfe0aacea83c4a86a3a10380cc2f3839114
Recipe-Nontrivial-Roll: build
Recipe-Nontrivial-Roll: build_limited
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/3352250Reviewed-by: Josip Sokcevic <sokcevic@google.com>
Commit-Queue: Garrett Beaty <gbeaty@google.com>

recipes/recipe_modules/bot_update/api.py

@@ -360,7 +360,7 @@ class BotUpdateApi(recipe_api.RecipeApi):
 
         if add_blamelists and 'manifest' in result:
           blamelist_pins = []
-          for name in revisions:
+          for name in sorted(revisions):
             m = result['manifest'][name]
             pin = {'id': m['revision']}
             pin['host'], pin['project'] = (