Description of problem:
Having a BPM cluster with two EAP 6.4 nodes in a domain, sometimes the second cluster node fails to deploy business central properly due to org.eclipse.jgit.api.errors.ConcurrentRefUpdateException: Could not lock HEAD. RefUpdate return code was: LOCK_FAILURE. Please take a look at attached server logs.

In Majority of attempts the issue does not occur, it's likely a synchronization problem. The first node seems to be working and responsive, the second node is completely lost when the issue happens.

Version-Release number of selected component (if applicable):
6.1.0.ER5

How reproducible:
10% - 20%

Steps to Reproduce:
1. configure two EAP 6.4 nodes in domain mode together with helix and zookeeper
2. deploy business central
3. watch for errors in server logs