Merge branch 'es/worktree-add' into maint

* es/worktree-add:
  worktree: usage: denote <branch> as optional with 'add'

diff --cc builtin/worktree.c
index 71bb770,8d85a8b..33d2d37
--- 1/builtin/worktree.c
--- 2/builtin/worktree.c
+++ b/builtin/worktree.c
@@@ -3,14 -3,11 +3,14 @@@
  #include "dir.h"
  #include "parse-options.h"
  #include "argv-array.h"
 +#include "branch.h"
 +#include "refs.h"
  #include "run-command.h"
  #include "sigchain.h"
 +#include "refs.h"
  
  static const char * const worktree_usage[] = {
-       N_("git worktree add [<options>] <path> <branch>"),
+       N_("git worktree add [<options>] <path> [<branch>]"),
        N_("git worktree prune [<options>]"),
        NULL
  };