[git-gui] bug report: "Open existing repository" dialog fails on submodules

Hi,

This bug report concerns git-gui. Apologies if this is not the right mailing-list.

By submodule I mean a repository for which .git is not a regular Git directory, but rather a "gitdir: ..." file. While running "git gui" from such a directory will work fine, trying to open it from the choose_repository window will fail with "Not a Git repository". This is because of the simplistic implementation of proc _is_git in lib/choose_repository.tcl.

I suggest fixing that function, or using Git directly to perform that check, for instance checking "git rev-parse --show-toplevel". I'd attempt a patch but my tcl-fu is weak.

Best