[jadbox]

This is why you rebase and test before each feature branch is to be merged to master. The only issue comes up when someone decides to merge while someone else has already rebased and is running their tests... but when they try to merge to master they will see their branch is out of date and that they need to rebase again. For small teams, it's easy enough to let everyone know that you're merging and not to merge anything else in the meantime. In a larger company, I've seen queue tools that give teams a 'ticket' for their turn to merge into master. It's a little clunky, and probably wouldn't scale to huge engineering teams... but sometimes low tech solutions work just as well.