Bug 12287 - Hold priority for new hold incorrect if record has holds in transit

When placing a new hold, the listed priority for the hold will be
incorrect if there are any holds with items in transit ( i.e. found = T ).

Test Plan:
1) Place 3 holds on a record with at least 2 items
2) Fill one hold so it is marked as waiting
3) Fill on hold so it is marked as in transit
4) Begin placing a new hold
5) Note the expected priority would be 2, but is actually 3
6) Apply this patch
7) Reload the patch, now the expected priority shows correctly

Signed-off-by: Coralie Barsacq <c.barsacq@mairie-laciotat.fr>

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>
Signed-off-by: Tomas Cohen Arazi <tomascohen@gmail.com>
Bug 12287: At the moment, found is 'W', 'T' or NULL

Just add a small comment to avoid any further ambiguity.

Signed-off-by: Jonathan Druart <jonathan.druart@biblibre.com>