'String prefix + lazy translated subject = bad output
Regression for #13494'

@override_settings(ADMINS=[(u'nobody', u'nobody+admin@example.com')], MANAGERS=[(u'nobody', u'nobody+manager@example.com')])
def test_manager_and_admin_mail_prefix(self):

    mail_managers(ugettext_lazy(u'Subject'), u'Content')
    message = self.get_the_message()
    self.assertEqual(message.get(u'subject'), u'[Django]    Subject')
    self.flush_mailbox()
    mail_admins(ugettext_lazy(u'Subject'), u'Content')
    message = self.get_the_message()
    self.assertEqual(message.get(u'subject'), u'[Django]    Subject')
