worktree: drop pointless strbuf_release()

The content of this strbuf is unconditionally detached several lines
before the strbuf_release() and the strbuf is never touched again after
that point.

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

worktree.c

@@ -66,8 +66,6 @@ static struct worktree *get_main_worktree(void)
 	worktree->is_bare = (is_bare_repository_cfg == 1) ||
 		is_bare_repository();
 	add_head_info(worktree);
-
-	strbuf_release(&worktree_path);
 	return worktree;
 }