Fixed #9383 -- Don't open a network connection for sending email if there's

nothing to send. Saves a bit of time when, for example, processing 500-error
emails with no ADMINs configured. Based on a patch from Jesse Young.


git-svn-id: http://code.djangoproject.com/svn/django/trunk@9248 bcc190cf-cafb-0310-a4f2-bffc1f526a37