Staff does not get the chats assigned in order

[winfried]

Observed on one chat on several occasions (verified by the logging): one staff member, the longest waiting, does not get a chat assigned. Could not reproduce the bug. Possibly the One2OneRoom.status_timestamp gets updated while waiting.

[winfried]

Bug is caused by a missing additional user info record for the staff, making her or him end up lower in this comparison:
order_by(
'-staff__user__additionaluserinformation__chat_priority',
'status_timestamp')

Workaround is making sure the user has a division assigned, causing the record to be created with the default priority. The record should always be created when creating a user.