LockTest#testLockKeepAliveReLocksDroppedLock sometimes fails

The following error is logged:
13.05.2015 03:22:24 ERROR [org.hippoecm.repository.impl.LockManagerDecorator$LockDecorator$1.run():221] Failed to refresh lock
javax.jcr.InvalidItemStateException: Unable to perform operation. Session has pending changes.
at org.apache.jackrabbit.core.ItemValidator.checkCondition(ItemValidator.java:269)
at org.apache.jackrabbit.core.ItemValidator.checkModify(ItemValidator.java:248)
at org.apache.jackrabbit.core.lock.SessionLockManager.lock(SessionLockManager.java:176)
at org.hippoecm.repository.impl.LockManagerDecorator$LockDecorator$1.run(LockManagerDecorator.java:214)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$201(ScheduledThreadPoolExecutor.java:180)
at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:293)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)