Make sure to test for unicode usernames, since the collate on the username field is latin1

data/model/legacy.py

@@ -792,6 +792,12 @@ def get_matching_users(username_prefix, robot_namespace=None,
 
 
 def verify_user(username_or_email, password):
+  # Make sure we didn't get any unicode for the username.
+  try:
+    str(username_or_email)
+  except ValueError:
+    return None
+
   try:
     fetched = User.get((User.username == username_or_email) |
                        (User.email == username_or_email))