[Koha] Reserve pending priority 0

[april]

System :
Koha 2.2.9, on fedora

Issue:
Under the Circulation >  Reserves Pending, the priority will 
occasionally get set to zero...even when the item is issued and the 
"cancel reserve" option is selected correctly during the issuing 
procedure. From that point on, onces the priority has been set to zero, 
there is no way to delete the reserve from the "reserves pending list".
The materials are correctly issued and tracked from that point on, but 
the "pending reserve request" with a priority of "0" seems to stick, and 
this list can grow quite large over time.

Is there a way to clear these from the list using the standard librarian 
interface ?

please help...

thanks