Don't set blamelist_pins on the json output.

The blamelist_pins attribute is being set on the json output, which is a
dictionary. This only works right now because json.output currently uses
OrderedDict as the dict type. With removal of support for python2, dict
could be used since its iteration order is insertion order in python3.
This change removes setting the blamelist_pins attribute since its not
used anywhere and it will allow json.output to use plain dict.

Change-Id: Ie19b87d61903774454df2d395acf695eaa39b201
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/4617204
Commit-Queue: Garrett Beaty <gbeaty@google.com>
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Aravind Vasudevan <aravindvasudev@google.com>
Auto-Submit: Garrett Beaty <gbeaty@google.com>
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Reviewed-by: Aravind Vasudevan <aravindvasudev@google.com>

recipes/README.recipes.md

@@ -62,7 +62,7 @@ Recipe module to ensure a checkout is consistent on a bot.
 
 Wrapper for easy calling of bot_update.
 
-— **def [deapply\_patch](/recipes/recipe_modules/bot_update/api.py#584)(self, bot_update_step):**
+— **def [deapply\_patch](/recipes/recipe_modules/bot_update/api.py#582)(self, bot_update_step):**
 
 Deapplies a patch, taking care of DEPS and solution revisions properly.
     
@@ -103,7 +103,7 @@ Args:
     change's commit message to get this revision override requested by the
     author.
 
-— **def [get\_project\_revision\_properties](/recipes/recipe_modules/bot_update/api.py#561)(self, project_name, gclient_config=None):**
+— **def [get\_project\_revision\_properties](/recipes/recipe_modules/bot_update/api.py#559)(self, project_name, gclient_config=None):**
 
 Returns all property names used for storing the checked-out revision of
 a given project.
@@ -119,7 +119,7 @@ Returns (list of str): All properties that'll hold the checked-out revision
 
 &emsp; **@property**<br>&mdash; **def [last\_returned\_properties](/recipes/recipe_modules/bot_update/api.py#34)(self):**
 
-&mdash; **def [resolve\_fixed\_revision](/recipes/recipe_modules/bot_update/api.py#512)(self, bot_update_json, name):**
+&mdash; **def [resolve\_fixed\_revision](/recipes/recipe_modules/bot_update/api.py#510)(self, bot_update_json, name):**
 
 Sets a fixed revision for a single dependency using project revision
 properties.

recipes/recipe_modules/bot_update/api.py

@@ -417,8 +417,6 @@ class BotUpdateApi(recipe_api.RecipeApi):
             pin['host'], pin['project'] = (
                 self.m.gitiles.parse_repo_url(m['repository']))
             blamelist_pins.append(pin)
-
-          result.blamelist_pins = blamelist_pins
           self.m.milo.show_blamelist_for(blamelist_pins)
 
         # Set output commit of the build.