Major Description
HBASE-17096 causes failures in UpgradeIT#testAcquiringAndReleasingUpgradeMutex. Essentially releasing of the upgrade mutex by using the checkAndMutate api isn't working correctly. A simple though not ideal work around would be to not call releaseMutex() and let the lock expire by the virtue of TTL set on the cell. The side effect is that if a client encounters and exception while executing the upgrade code, then a new client won't be able to initiate the upgrade till the TTL expires.