Merging the child topic in stacked topics does not detect the merge in parent topics
Summary
Merging the child topic in stacked topics does not detect the merge in parent topics
Steps to reproduce
Stack a topic B on top of topic A, merge B through the UI.
What is the current bug behavior?
Since the project is in a fast-forward configuration, A asks for a rebase after B was merged. If you click the rebase button, it will correctly update the MR, wrongly (IMO) launch the CI then detect it was merged when B was merged.
What is the expected correct behavior?
A should detect that it has been merged and not need a rebase nor launch the CI.
Results of GitLab environment info
Seen on heptapod.host, with version Heptapod 0.12.1 134404556166 (GitLab CE 12.2.12)