Regenerate username if it's empty after slugification

apps/users/tests/test_user_utils.py

@@ -31,6 +31,10 @@ class TestAutoCreateUsername(amo.tests.TestCase):
         eq_(autocreate_username('testaccount+slug'),
             'testaccountslug')
 
+    def test_empty_username_is_a_random_hash(self):
+        un = autocreate_username('.+')  # this shouldn't happen but it could!
+        assert len(un) and not un.startswith('.+'), 'Unexpected: %s' % un
+
     def test_blacklisted(self):
         BlacklistedUsername.objects.create(username='firefox')
         un = autocreate_username('firefox')

apps/users/utils.py

@@ -113,9 +113,9 @@ def autocreate_username(candidate, tries=1):
     adjusted_u = make_u(candidate)
     if tries > 1:
         adjusted_u = '%s%s' % (adjusted_u, tries)
-    if (BlacklistedUsername.blocked(adjusted_u)
+    if (BlacklistedUsername.blocked(adjusted_u) or adjusted_u == ''
         or tries > max_tries or len(adjusted_u) > 255):
-        log.info('username blocked, max tries reached, or too long;'
+        log.info('username blocked, empty, max tries reached, or too long;'
                  ' username=%s; max=%s' % (adjusted_u, max_tries))
         return autocreate_username(uuid.uuid4().hex[0:15])
     if UserProfile.objects.filter(username=adjusted_u).count():