[abrezas]

The problem is not if someone merges a PR before you push, but if someone branches off of the current tip of master, works on it, you remove that tip, and your colleague now is based on a history that doesn't exist, has to resolve your conflicts.

[hashkb]

They're the same conflicts they'd have to fix if I pushed a new commit or merged a PR; assuming I made the same changes to code when I force pushed.