Backport 'Rebase' feature from EE to CEjprovazn-rebase

When a project uses fast-forward merging strategy user has
to rebase MRs to target branch before it can be merged.
Now user can do rebase in UI by clicking 'Rebase' button
instead of doing rebase locally.

This feature was already present in EE, this is only backport
of the feature to CE. Couple of changes:
* removed rebase license check
* renamed migration (changed timestamp)

Closes #40301

1 files changed, 16 insertions, 0 deletions

diff --git a/spec/serializers/merge_request_widget_entity_spec.rb b/spec/serializers/merge_request_widget_entity_spec.rb
index e25552eb0d8..80a271ba7fb 100644
--- a/spec/serializers/merge_request_widget_entity_spec.rb
+++ b/spec/serializers/merge_request_widget_entity_spec.rb
@@ -190,4 +190,20 @@ describe MergeRequestWidgetEntity do
       end
     end
   end
+
+  describe 'when source project is deleted' do
+    let(:project) { create(:project, :repository) }
+    let(:fork_project) { create(:project, :repository, forked_from_project: project) }
+    let(:merge_request) { create(:merge_request, source_project: fork_project, target_project: project) }
+
+    it 'returns a blank rebase_path' do
+      allow(merge_request).to receive(:should_be_rebased?).and_return(true)
+      fork_project.destroy
+      merge_request.reload
+
+      entity = described_class.new(merge_request, request: request).as_json
+
+      expect(entity[:rebase_path]).to be_nil
+    end
+  end
 end