bug#3968: 23.1.50 vc-dir shows error message

when run vc-dir, the minibuffer reads:

vc-git-stash-list: Wrong type argument: arrayp, nil

In GNU Emacs 23.1.50.1 (i386-mingw-nt5.1.2600)
 of 2009-07-30 on HIH-D-403
Windowing system distributor `Microsoft Corp.', version 5.1.2600
configured using `configure --with-gcc (4.4)'