git-repack: allow git-repack to run in subdirectory

Now that we explicitly create all tmpfiles below $GIT_DIR, there's no reason
to care about which directory we're in.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

git-repack.sh

@@ -4,6 +4,7 @@
 #
 
 USAGE='[-a] [-d] [-f] [-l] [-n] [-q]'
+SUBDIRECTORY_OK='Yes'
 . git-sh-setup
 
 no_update_info= all_into_one= remove_redundant=