[bug] assertion in 2.8.4 triggering on old-ish worktree

Hi All,

I have the git-sh-prompt configured in my .bashrc today I visited an
old worktree that I haven't really touched in a few years (sorry can't
remember the git version I was using back then). I received the
following output when changing to the directory

git: pathspec.c:317: prefix_pathspec: Assertion `item->nowildcard_len
<= item->len && item->prefix <= item->len' failed.

I assume it's one of the git invocations in git-sh-prompt that's
hitting the assertion. Any thoughts on what might be triggering it?
Any debug I can gather?