checkout: die_if_checked_out: simplify strbuf management

There is no reason to keep the strbuf active long after its last use.
By releasing it as early as possible, resource management is simplified
and there is less worry about future changes resulting in a leak.

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/checkout.c

@@ -924,17 +924,16 @@ static void die_if_checked_out(struct branch_info *new)
 	check_linked_checkout(new, NULL);
 
 	strbuf_addf(&path, "%s/worktrees", get_git_common_dir());
-	if ((dir = opendir(path.buf)) == NULL) {
-		strbuf_release(&path);
+	dir = opendir(path.buf);
+	strbuf_release(&path);
+	if (!dir)
 		return;
-	}
 
 	while ((d = readdir(dir)) != NULL) {
 		if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
 			continue;
 		check_linked_checkout(new, d->d_name);
 	}
-	strbuf_release(&path);
 	closedir(dir);
 }