Merge trains should retry failed merges
Problem to solve
When I click merge, I expect the merge request to be merged. But when using Merge Trains, some of the properties of the merge button change - particularly, if the merge fails, I am not notified that the merge request has been removed the merge train, and if it is a transient failure, I end up at the back of the merge train.
- Retry if a merge train merge fails so I don't lose my spot because of a random API failure
Notify my of the failure(handling of notification to the user when an MR is dropped from a train is issue #12136)