Merge even if master is updated

Right now if I press the merge button but master is updated it fails and I have to refresh and press merge again.

I don't think there is a good reason for this, if it can it should just merge, even if is master is ahead.

/cc @JobV @dzaporozhets @DouweM

Title changed from Merge even is master is updated to Merge even if master is updated

Agree.

Added frontend label

Milestone changed to 8.6

Added ~123454 label

Added ~122770 label

Job: "this is basically a bug"

Removed frontend label

Reassigned to @rdavila

@sytses I just want to double check if it's a race condition error, I've tried 2 scenarios in order to reproduce the bug and I was only able to reproduce the error when the repo was being receiving updates and I tried to merge at the same time:

Scenario 1 (good)

1. open a MR against master
2. Send some updates to the master branch (now master is ahead)
3. Merge the MR without previously refreshing the page.
4. MR is merged without any issues

Scenario 2 (bad)

1. open a MR against master
2. Send some updates to master through a bash loop:

for i in {1..50000};do echo "Add line $i" >> data.txt;git add data.txt;git ci -m "Update #$i";git push origin master;done

3. Now try to accept the MR
4. An error is being shown:

Can you confirm that the above screen is what you were seeing when trying to merge?

@rdavila I'm sorry but I'm not sure if that was what I saw. I'm surprised that scenario 1 already works in GitLab, that was what I created this issue for. If this already works we're done. I can live with the race condition in 2.

@sytses ok, I'm going to close this in the meantime and please reopen it if it happens again. Thanks.

Status changed to closed

Thanks @rdavila

I think this was inadvertently fixed by https://gitlab.com/gitlab-org/gitlab-ce/commit/097faeb481db2a4956b41049c041d55f5da4e2c1, which will always refresh the MR's mergeability status before a merge.

mentioned in issue #13266 (closed)