Parallel agenda freezes when running fireUntilHalt on multiple KieSessions

Parallel agenda freezes when running in multiple KieSessions. Reproducer is in "testMultipleParallelKieSessionsFireUntilHalt" test from https://github.com/kiegroup/drools/pull/1164/commits/b3d8edee350b4e05101f9ebb1ee96443a449d78f

Reproducer does the following steps:

1. Create kie base.
2. Run 5 separate threads.
3. Each thread creates its own kie session with parallel agenda enabled.
4. Run fire until halt on its own kie session.