jenkinsci/external-resource-dispatcher-plugin — pull request #3 by EBichel (2013-08-23 10:51:10+00:00)
Title: Bugfix: Deadlock in queue when lease/reservation runs out

As an example, if Job A locked a resource and Job B reserved a resource but was postponed for a later execution, the reservation was still stored in the ReservedExternalResourceAction even though the lease time run out . This leads to a dead lock for the Job B, because it can't reserve another resource in the ExternalResourceQueueTaskDispatcher ever again.