b1ef400e (setup_git_env: avoid blind fall-back to ".git") made programs
that tried to access a repository without initializing properly die with
a diagnostic message. One offender is test-read-cache, which is used in
p0002. Fix it by calling setup_git_directory() before accessing the
index.
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>