stop ProcessCommitWorker from processing MR merge commit

When a merge request is merged, it creates a commit with the
description of the MR, which may contain references and issue
closing references. As this will be handled in the PostMergeService
anyways, let's ignore merge commit generated from a MR.

2 files changed, 9 insertions, 11 deletions

diff --git a/app/models/commit.rb b/app/models/commit.rb
index 8c960389652..add5fcf0e79 100644
--- a/app/models/commit.rb
+++ b/app/models/commit.rb
@@ -417,6 +417,10 @@ class Commit
     !!(title =~ WIP_REGEX)
   end
 
+  def merged_merge_request?(user)
+    !!merged_merge_request(user)
+  end
+
   private
 
   def commit_reference(from, referable_commit_id, full: false)
@@ -445,10 +449,6 @@ class Commit
     changes
   end
 
-  def merged_merge_request?(user)
-    !!merged_merge_request(user)
-  end
-
   def merged_merge_request_no_cache(user)
     MergeRequestsFinder.new(user, project_id: project.id).find_by(merge_commit_sha: id) if merge_commit?
   end
diff --git a/app/workers/process_commit_worker.rb b/app/workers/process_commit_worker.rb
index 52eebe475ec..a6330a6c51f 100644
--- a/app/workers/process_commit_worker.rb
+++ b/app/workers/process_commit_worker.rb
@@ -23,27 +23,25 @@ class ProcessCommitWorker
     return unless user
 
     commit = build_commit(project, commit_hash)
-
     author = commit.author || user
 
-    process_commit_message(project, commit, user, author, default)
+    # this is a GitLab generated commit message, ignore it.
+    return if commit.merged_merge_request?(user)
 
+    process_commit_message(project, commit, user, author, default)
     update_issue_metrics(commit, author)
   end
 
   def process_commit_message(project, commit, user, author, default = false)
     closed_issues = default ? commit.closes_issues(user) : []
 
-    unless closed_issues.empty?
-      close_issues(project, user, author, commit, closed_issues)
-    end
-
+    close_issues(project, user, author, commit, closed_issues) if closed_issues.any?
     commit.create_cross_references!(author, closed_issues)
   end
 
   def close_issues(project, user, author, commit, issues)
     # We don't want to run permission related queries for every single issue,
-    # therefor we use IssueCollection here and skip the authorization check in
+    # therefore we use IssueCollection here and skip the authorization check in
     # Issues::CloseService#execute.
     IssueCollection.new(issues).updatable_by_user(user).each do |issue|
       Issues::CloseService.new(project, author)