Merge branch 'sh-fix-merge-request-stickiness' into 'master'

Clear merge request error on push to source branch

Closes #34186

See merge request gitlab-org/gitlab!32001

app/services/merge_requests/refresh_service.rb

@@ -115,6 +115,10 @@ module MergeRequests
       filter_merge_requests(merge_requests).each do |merge_request|
         if branch_and_project_match?(merge_request) || @push.force_push?
           merge_request.reload_diff(current_user)
+          # Clear existing merge error if the push were directed at the
+          # source branch. Clearing the error when the target branch
+          # changes will hide the error from the user.
+          merge_request.merge_error = nil
         elsif merge_request.merge_request_diff.includes_any_commits?(push_commit_ids)
           merge_request.reload_diff(current_user)
         end

changelogs/unreleased/sh-fix-merge-request-stickiness.yml

+---
+title: Clear merge request error on push to source branch
+merge_request: 32001
+author:
+type: fixed

spec/services/merge_requests/refresh_service_spec.rb

@@ -94,6 +94,31 @@ describe MergeRequests::RefreshService do
         expect(@fork_build_failed_todo).to be_done
       end
 
+      context 'when a merge error exists' do
+        let(:error_message) { 'This is a merge error' }
+
+        before do
+          @merge_request = create(:merge_request,
+            source_project: @project,
+            source_branch: 'feature',
+            target_branch: 'master',
+            target_project: @project,
+            merge_error: error_message)
+        end
+
+        it 'clears merge errors when pushing to the source branch' do
+          expect { refresh_service.execute(@oldrev, @newrev, 'refs/heads/feature') }
+            .to change { @merge_request.reload.merge_error }
+            .from(error_message)
+            .to(nil)
+        end
+
+        it 'does not clear merge errors when pushing to the target branch' do
+          expect { refresh_service.execute(@oldrev, @newrev, 'refs/heads/master') }
+            .not_to change { @merge_request.reload.merge_error }
+        end
+      end
+
       it 'reloads source branch MRs memoization' do
         refresh_service.execute(@oldrev, @newrev, 'refs/heads/master')