Fix sorting by priority with filtering by approvers

ee/app/models/ee/merge_request.rb

@@ -36,7 +36,7 @@ module EE
 
     class_methods do
       def select_from_union(relations)
-        from_union(relations, remove_duplicates: true)
+        where(id: from_union(relations))
       end
     end
 

ee/changelogs/unreleased/id-500-filter-by-approver-and-priority.yml

+---
+title: Fix sorting by priority with filtering by approvers
+merge_request: 10446
+author:
+type: fixed

ee/spec/finders/merge_requests/by_approvers_finder_spec.rb

@@ -133,4 +133,19 @@ describe MergeRequests::ByApproversFinder do
       )
     end
   end
+
+  context 'filter by approvers' do
+    let(:mrs_by_ids) { merge_requests(ids: [first_user.id]) }
+    let(:mrs_by_usernames) { merge_requests(names: [first_user.username]) }
+
+    it 'can be ordered by popularity' do
+      expect(mrs_by_ids.sort_by_attribute("popularity")).to eq([merge_request_with_two_approvers, merge_request_with_approver])
+      expect(mrs_by_usernames.sort_by_attribute("popularity")).to eq([merge_request_with_two_approvers, merge_request_with_approver])
+    end
+
+    it 'can be ordered by priority' do
+      expect(mrs_by_usernames.sort_by_attribute("priority")).to eq([merge_request_with_two_approvers, merge_request_with_approver])
+      expect(mrs_by_ids.sort_by_attribute("priority")).to eq([merge_request_with_two_approvers, merge_request_with_approver])
+    end
+  end
 end