Since it's too hard to use JOIN with Rails... feedback:

app/models/project.rb

@@ -431,13 +431,13 @@ class Project < ActiveRecord::Base
 
   # ref can't be HEAD, can only be branch/tag name or SHA
   def latest_successful_builds_for(ref = default_branch)
-    pipeline = pipelines.latest_successful_for(ref).to_sql
-    join_sql = "INNER JOIN (#{pipeline}) pipelines" +
-               " ON pipelines.id = #{Ci::Build.quoted_table_name}.commit_id"
-    builds.joins(join_sql).latest.with_artifacts
-    # TODO: Whenever we dropped support for MySQL, we could change to:
-    # pipeline = pipelines.latest_successful_for(ref)
-    # builds.where(pipeline: pipeline).latest.with_artifacts
+    latest_pipeline = pipelines.latest_successful_for(ref).first
+
+    if latest_pipeline
+      latest_pipeline.builds.latest.with_artifacts
+    else
+      builds.none
+    end
   end
 
   def merge_base_commit(first_commit_id, second_commit_id)