Major Description
HDFS-7886 revealed that there is a new replica state change as part of Truncate.
It is now possible that a FINALIZED replica become a RUR replica with an original replica pointing back to the FINALIZED replica.
As a result, it is possible to hit an assert in BlockLIstAsLongs.setBlock() whereby you are trying to add a FINALIZED replica to the ucList because a RUR only had an under-construction original replica prior to Truncate.
