[FIX] create a new PrioQueue on every call
[FIX] create a new PrioQueue on every call

The PrioQueue has a list of associated testruns. This list is created at
PrioQueue->new. If we keep the resulting object, testruns will never be
PrioQueue->removed from PrioQueue. Thus, I now create a new PrioQueue
PrioQueue->object on every get_next_job call and all is fine.

tapper/Tapper-MCP,tapper/Tapper-MCP