Our remote master branch somehow got messed up. Current development code is on the master branch along with the latest commits. Obviously, the development code is not ready
For me, @svick 's hint pointed in the right direction. Since the git server I wanted to modify is actually my box, I logged into it and did a git config --global receive.denynonfastforwards false to change all repos to accept a forced non-ff push. Didn't work out of the box. What I found was that in the config there already was receive.denynonfastforwards=true set, and it couldn't be erased with git config --global --unset receive.denynonfastforwards.
Doing the edit in the repo manually (vi config) worked, though.