Make the rest of commands work from a subdirectory.

These commands are converted to run from a subdirectory.

    commit-tree convert-objects merge-base merge-index mktag
    pack-objects pack-redundant prune-packed read-tree tar-tree
    unpack-file unpack-objects update-server-info write-tree

Signed-off-by: Junio C Hamano <junkio@cox.net>

commit-tree.c

@@ -91,6 +91,8 @@ int main(int argc, char **argv)
 	if (argc < 2 || get_sha1_hex(argv[1], tree_sha1) < 0)
 		usage(commit_tree_usage);
 
+	setup_git_directory();
+
 	check_valid(tree_sha1, "tree");
 	for (i = 2; i < argc; i += 2) {
 		char *a, *b;