[1.2.X] Ensure that the sitemaps test deactivates it's locale, so that...

[1.2.X] Ensure that the sitemaps test deactivates it's locale, so that subsequent tests aren't run in French.

Backport of r14078 from trunk.

git-svn-id: http://code.djangoproject.com/svn/django/branches/releases/1.2.X@14080 bcc190cf-cafb-0310-a4f2-bffc1f526a37