call git_config() after setup_git_directory()

If you call setup_git_directory() to work from a subdirectory,
that should be run first before running git_config().  Otherwise
you would not read the configuration file from the correct place.

Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/show-branch.c b/show-branch.c
index ffe7456..511fd3b 100644
--- a/show-branch.c
+++ b/show-branch.c
@@ -548,8 +548,8 @@
 	int with_current_branch = 0;
 	int head_at = -1;
 
-	git_config(git_show_branch_config);
 	setup_git_directory();
+	git_config(git_show_branch_config);
 
 	/* If nothing is specified, try the default first */
 	if (ac == 1 && default_num) {