The test expects that "chmod -r ~/.git-credentials" would make it
unreadable to the user, and thus needs the SANITY prerequisite.
Reported-by: NJean-Yves LENHOF <jean-yves@lenhof.eu.org>
Signed-off-by: NPaul Tan <pyokagan@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>