git push requires a worktree?

I am doing a funny thing where I do git -C .git/modules/morx push
fleem:fleem.  This is failing in the case where I have a sparse
checkout and the worktree directory "morx" (which is where
.git/modules/morx/config's core.worktree points) doesn't exist.  

I don't know why git push cares about the worktree -- it'll happily
work in a bare repo with no worktree at all, or if the worktree is an
unrelated git repo or whatever.

I can work around it, but if there's a bug, I think we should fix it.