FWIW I also think we'd change the default to "upstream". The problem
with this default is that most repos only have one branch (master) and
thus they never run into this problem, so most people don't get the
habit to modify push.default AND they get the (bad) habit of typing
"git push". Then they work with multiple branches and get unexpected
pushes (with or without --force, especially when sausage making).
I know it's "their" fault for not learning more about git push's
defaults, but the current default is clearly against the principle of
least surprise IMHO.
Philippe