[3.13] Fix unlikely potential reference leak in _locale._getdefaultlocale (GH-145250) (GH-145303)

It occurs in a code which perhaps never executed.
(cherry picked from commit 6ea84b2726bb6a1a8a6819d30c368ac34c50eabe)

Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>