Feature Request: optionally initialize git submodule for the worktree

[fancl20]

Context: currently all submodules under a worktree is uninitialized.

Using git submodule with worktree is buggy: https://stackoverflow.com/questions/31871888/what-goes-wrong-when-using-git-worktree-with-git-submodules but could still be useful.

[ethanndickson]

This seems like a good candidate for a init hook? Curious to hear how that goes for you.