Fixed #17628 -- Extended makemessages command to also ignore directories when...

Fixed #17628 -- Extended makemessages command to also ignore directories when walking, not only when looking for files. Thanks, Claude Paroz.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@17441 bcc190cf-cafb-0310-a4f2-bffc1f526a37