Nice overview. There is a lot of rebasing going on, and I wonder how that would work when more than one person works on the downstream fork. Force-pushing can easily break other users’ checkouts.
- never force push a branch
- at least not if someone else could be working on it
- and definitely not without talking to them about it
Personally I force push my branches quite often. It's super useful to rebase my branch on to main/master or doing an interactive rebase to reorder my commits, merge or just change the commit message.
I've been on the other end of someone rebasing and force pushing. I've found that just removing the branch from my local git and then checking it out fresh from origin is the simplest way to go.
With such a loose relation you could easily end up in a situation where you are conceptually “force pushing”. Because you might use the same patches but not have the same graph topology.
What if you send three patches to the upstream and they incorporate it with git-am(1)? Then they have effectively made a different history with your patches: three commits which are not the same as your three but may be patch-identical. Then you need to keep track of that “force push” by the upstream so that you don’t maintain your now duplicate commits (as in distinct commits but the changes are duplicates).