Bug 11956

In the process of testing bug 11947, discovered that if a hold is triggered as in transit to another branch and a new hold is added to the record later, the new hold gets a larger priority number than expected. 

Test plan to recreate:

1. Add six holds to a record, the first one needs to have a pickup location of a different branch than what you are logged in as. 
2. Trigger the hold for the first patron so the item goes into transit. 
3. Note that the holds priority for the record is now In Transit; 1; 2; 3; 4; 5. 
4. Add a hold for another patron to the same record. 
5. You expect a holds priority of 6, but it is set as 7. 
6. Add a hold for another patron to the same record.
7. You expect a holds priority of 7, but it is set as 8.