add specs for post ownership change without revision

spec/services/post_owner_changer_spec.rb

@@ -51,6 +51,13 @@ describe PostOwnerChanger do
       expect(p2.user).not_to eq(user_a)
     end
 
+    it "skips creating new post revision if skip_revision is true" do
+      described_class.new(post_ids: [p1.id, p2.id], topic_id: topic.id, new_owner: user_a, acting_user: editor, skip_revision: true).change_owner!
+      p1.reload; p2.reload
+      expect(p1.revisions.size).to eq(0)
+      expect(p2.revisions.size).to eq(0)
+    end
+
     context "integration tests" do
       let(:p1user) { p1.user }
       let(:p2user) { p2.user }