Revert "Do not create a MergeRequestDiff record when source branch is deleted"

This reverts commit f913170e.

app/services/merge_requests/refresh_service.rb

@@ -60,7 +60,15 @@ module MergeRequests
       merge_requests = filter_merge_requests(merge_requests)
 
       merge_requests.each do |merge_request|
-        reload_diff(merge_request) unless branch_removed?
+        if merge_request.source_branch == @branch_name || force_push?
+          merge_request.reload_diff
+        else
+          mr_commit_ids = merge_request.commits.map(&:id)
+          push_commit_ids = @commits.map(&:id)
+          matches = mr_commit_ids & push_commit_ids
+          merge_request.reload_diff if matches.any?
+        end
+
         merge_request.mark_as_unchecked
       end
     end
@@ -165,16 +173,5 @@ module MergeRequests
     def branch_removed?
       Gitlab::Git.blank_ref?(@newrev)
     end
-
-    def reload_diff(merge_request)
-      if merge_request.source_branch == @branch_name || force_push?
-        merge_request.reload_diff
-      else
-        mr_commit_ids = merge_request.commits.map(&:id)
-        push_commit_ids = @commits.map(&:id)
-        matches = mr_commit_ids & push_commit_ids
-        merge_request.reload_diff if matches.any?
-      end
-    end
   end
 end

changelogs/unreleased/fix-merge-request-screen-deleted-source-branch.yml

----
-title: Do not create a MergeRequestDiff record when source branch is deleted
-merge_request: 7481
-author:

spec/services/merge_requests/refresh_service_spec.rb

@@ -227,16 +227,6 @@ describe MergeRequests::RefreshService, services: true do
       end
     end
 
-    context 'when the source branch is deleted' do
-      it 'does not create a MergeRequestDiff record' do
-        refresh_service = service.new(@project, @user)
-
-        expect do
-          refresh_service.execute(@oldrev, Gitlab::Git::BLANK_SHA, 'refs/heads/master')
-        end.not_to change { MergeRequestDiff.count }
-      end
-    end
-
     def reload_mrs
       @merge_request.reload
       @fork_merge_request.reload