Bug: moving submodules that have submodules inside them causes a fatal error in git status

Hello,

I encountered this error when moving some submodules in vim, basically if you
have a submodule that has submodules inside it and you try to move it you'll
encouter a fatal error with `git status`. I have a pastebin example of this
here: https://ptpb.pw/5g9-/bash

Appologies if this is an invalid bug report.

I'm running Git version: 2.16.2 (Debian Unstable)

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Sean Behan