DKRON busy bug

Reproduce bug where DKRON jobs stay "stuck" in the busy state. See this bug report in GitHub.

Steps to reproduce:

1. Check out this repository locally.
2. Run docker-compose up --force-recreate -d. This will create clusters for DKRON 3.2.6, 3.2.7, and 4.0.2.
3. Wait a minute for DKRON to stabilize and then run addRedisJobs.sh to create test jobs in each DKRON cluster.
4. Wait about 15 minutes.
5. Check the busy tab for each DKRON version:
   1. http://localhost:8080/ui/#/busy (DKRON 3.2.6)
   2. http://localhost:8081/ui/#/busy (DKRON 3.2.7)
   3. http://localhost:8082/ui/#/busy (DKRON 4.0.2)

Expected result

All DKRON UIs show no busy jobs older than 10 seconds.

Actual result

DKRON 3.2.6 shows no busy jobs older than 10 seconds. DKRON versions newer than 3.2.6 show multiple "stuck" jobs.