Hello,
Today I tried to push this change: https://gerrit.wikimedia.org/r/#/c/338326/ and it quickly got -1 from Jenkins bot.
After a few tests trying to rebase the change manually, and remove the tabs and so forth, there was no way it would get +1.
@Volans and @jcrespo also tried to debug the issue without finding anything.
In order to discard issues with that specific commit and/or file we tried different test commits even on other files, and they always got -1:
https://gerrit.wikimedia.org/r/338335
https://gerrit.wikimedia.org/r/338334
https://gerrit.wikimedia.org/r/338331
We forced a +2 and it got merged successfully so looks like cobalt isn't the issue but the copy the jenkins bot is using.
After getting it merged, a git pull on another old copy shows the merge and the file without any issue.