Sanity check pipeline sha before saving merge request head pipeline

app/services/ci/create_pipeline_service.rb

@@ -119,8 +119,14 @@ module Ci
     end
 
     def update_merge_requests_head_pipeline
-      MergeRequest.where(source_branch: @pipeline.ref, source_project: @pipeline.project).
-        update_all(head_pipeline_id: @pipeline.id)
+      merge_requests = MergeRequest.where(source_branch: @pipeline.ref, source_project: @pipeline.project)
+
+      merge_requests_ids =
+        merge_requests.select do |mr|
+          mr.diff_head_sha == @pipeline.sha
+        end.map(&:id)
+
+      MergeRequest.where(id: merge_requests_ids).update_all(head_pipeline_id: @pipeline.id)
     end
 
     def error(message, save: false)

changelogs/unreleased/issue_32225_2.yml

+---
+title: Sanity check for pipeline sha before saving merge request pipeline id
+merge_request:
+author:

spec/services/ci/create_pipeline_service_spec.rb

@@ -58,7 +58,7 @@ describe Ci::CreatePipelineService, services: true do
         end
 
         context 'when merge request target project is different from source project' do
-          let!(:target_project) { create(:empty_project) }
+          let!(:target_project) { create(:project) }
           let!(:forked_project_link) { create(:forked_project_link, forked_to_project: project, forked_from_project: target_project) }
 
           it 'updates head pipeline for merge request' do
@@ -70,6 +70,17 @@ describe Ci::CreatePipelineService, services: true do
             expect(merge_request.reload.head_pipeline).to eq(head_pipeline)
           end
         end
+
+        context 'when merge request head commit sha does not match pipeline sha' do
+          it 'does not update merge request head pipeline' do
+            merge_request = create(:merge_request, source_branch: 'master', target_branch: "branch_1", source_project: project)
+            allow_any_instance_of(MergeRequestDiff).to receive(:head_commit).and_return(double(id: 1234))
+
+            pipeline
+
+            expect(merge_request.reload.head_pipeline).to be_nil
+          end
+        end
       end
 
       context 'auto-cancel enabled' do