Fix setbotcommit comment on ambiguous revision

Add revision number option to gerrit_client.py setbotcommit command. Add
an explicit revision number to a setbotcommit call in the update_files
method.

After creating a new patch-set in the release recipe and verifying it
was created we are adding a comment which could be applied to the
previous patch. Setting `Bot-Commit+1` relied on the default 'current'
revision which may be stale in some Gerrit replicas. This CL applies the
fix suggested in 412739202

Bug: 414681998
Change-Id: I1d380e221864bcf1183c77fa58be4ede9a787ef1
Recipe-Nontrivial-Roll: build_internal
Recipe-Nontrivial-Roll: chrome_release
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6718447
Reviewed-by: Alex Kravchuk <alexanderkr@google.com>
Reviewed-by: Scott Lee <ddoman@chromium.org>

recipes/recipe_modules/gerrit/api.py

@@ -558,13 +558,16 @@ class GerritApi(recipe_api.RecipeApi):
       publish_command.append('--verbose')
     self('publish edit', publish_command)
 
+    NEW_PATCHSET_REVISION_NUMBER = 2
     # Make sure the new patchset is propagated to Gerrit backend.
     with self.m.step.nest('verify the patchset exists on CL %d' % change):
       retries = 0
       max_retries = 2
       while retries <= max_retries:
         try:
-          if self.get_revision_info(host, change, 2):
+          if self.get_revision_info(host,
+                                    change,
+                                    patchset=NEW_PATCHSET_REVISION_NUMBER):
             break
         except self.m.step.InfraFailure:
           if retries == max_retries:  # pragma: no cover
@@ -580,6 +583,8 @@ class GerritApi(recipe_api.RecipeApi):
           host,
           '--change',
           change,
+          '--revision',
+          NEW_PATCHSET_REVISION_NUMBER,
       ]
       if verbose:
         set_bot_commit_command.append('--verbose')