Make "merge ongoing" check more consistent

app/models/merge_request.rb

@@ -396,7 +396,7 @@ class MergeRequest < ActiveRecord::Base
   end
 
   def merge_ongoing?
-    !!merge_jid && !merged?
+    !!merge_jid && !merged? && Gitlab::SidekiqStatus.num_running([merge_jid]) > 0
   end
 
   def closed_without_fork?

changelogs/unreleased/39032-improve-merge-ongoing-check-consistency.yml

@@ -0,0 +1,5 @@
+---
+title: Make "merge ongoing" check more consistent
+merge_request:
+author:
+type: fixed

spec/models/merge_request_spec.rb

@@ -1460,11 +1460,31 @@ describe MergeRequest do
   end
 
   describe '#merge_ongoing?' do
-    it 'returns true when merge_id is present and MR is not merged' do
+    it 'returns true when merge_id, MR is not merged and it has no running job' do
       merge_request = build_stubbed(:merge_request, state: :open, merge_jid: 'foo')
+      allow(Gitlab::SidekiqStatus).to receive(:num_running).with(['foo']) { 1 }
 
       expect(merge_request.merge_ongoing?).to be(true)
     end
+
+    it 'returns false when merge_jid is nil' do
+      merge_request = build_stubbed(:merge_request, state: :open, merge_jid: nil)
+
+      expect(merge_request.merge_ongoing?).to be(false)
+    end
+
+    it 'returns false if MR is merged' do
+      merge_request = build_stubbed(:merge_request, state: :merged, merge_jid: 'foo')
+
+      expect(merge_request.merge_ongoing?).to be(false)
+    end
+
+    it 'returns false if there is no merge job running' do
+      merge_request = build_stubbed(:merge_request, state: :open, merge_jid: 'foo')
+      allow(Gitlab::SidekiqStatus).to receive(:num_running).with(['foo']) { 0 }
+
+      expect(merge_request.merge_ongoing?).to be(false)
+    end
   end
 
   describe "#closed_without_fork?" do