On https://gerrit.wikimedia.org/r/c/mediawiki/vendor/+/844035, I CR+2 the patch to get it premerged so I could control when to do the deployment and not be caught by surprise.

I then ran scap backport 844035. It then approved the change, waited for it to be merged and then found it merged (obviously):

Backport the changes? (y/n): y
14:25:09 Voting on 1 change(s)
14:25:09 Change 844035 approved
14:25:09 Waiting for changes to be merged. This may take some time if there are long running tests.
14:25:09 awaiting-backport-merges: 100% (ok: 1; fail: 0; left: 0)               
14:25:09 All changes have been merged

I guess before voting, we could check whether the change already got merged by querying Gerrit.