Other rational companies could try to fix this without contributing upstream. Doing it upstream benefits competitors like gitlab. So yeah! It's nice seeing this kind of behavior
First, they not only contributed upstream, upstream developers contributed to this patch. I.e. they got help outside GitHub to make this patch possible.
Second, if they had decided to fork Git, then they'd have to maintain this fork forever.
Third, this fork could overtime become visibly or even worse subtly incompatible with stock Git which is still the Git running on GitHub users' machines, and both should interact with each other in 100% compatible manner.
So, in this case, not contributing upstream was literally no-go. The only rational choice would be to not fork Git.
