add test for bug in git-mv for recursive submodules
When using git-mv with a submodule it will detect that and update the
paths for its configurations (.gitmodules, worktree and gitfile). This
does not work for recursive submodules where a user renames the root
submodule.
We discovered this fact when working on on-demand fetch for renamed
submodules. Lets add a test to document.
Signed-off-by: Heiko Voigt <hvoigt@hvoigt.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>