Fix buildbucket bug filing instructions

Use Infra>Platform>Buildbucket component, not Infra-BuildBucket label.

R=qyearsley

Bug: 849361
Change-Id: I27706d93097a20c6927ffa5405550bb63aa519dd
Reviewed-on: https://chromium-review.googlesource.com/1085898Reviewed-by: Quinten Yearsley <qyearsley@chromium.org>
Commit-Queue: Nodir Turakulov <nodir@chromium.org>

git_cl.py

@@ -354,7 +354,8 @@ def _buildbucket_retry(operation_name, http, *args, **kwargs):
       if not content_json:
         raise BuildbucketResponseException(
             'Buildbucket returns invalid json content: %s.\n'
-            'Please file bugs at http://crbug.com, label "Infra-BuildBucket".' %
+            'Please file bugs at http://crbug.com, '
+            'component "Infra>Platform>BuildBucket".' %
             content)
       return content_json
     if response.status < 500 or try_count >= 2: