setup: set the_repository's hash algo when checking format

When we're checking the repository's format, set the hash algorithm at
the same time.  This ensures that we perform a suitable initialization
early enough to avoid confusing any parts of the code.  If we defer
until later, we can end up with portions of the code which are confused
about the hash algorithm, resulting in segfaults when working with
SHA-256 repositories.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

setup.c

@@ -1273,6 +1273,7 @@ void check_repository_format(struct repository_format *fmt)
 		fmt = &repo_fmt;
 	check_repository_format_gently(get_git_dir(), fmt, NULL);
 	startup_info->have_repository = 1;
+	repo_set_hash_algo(the_repository, fmt->hash_algo);
 	clear_repository_format(&repo_fmt);
 }