Tez 0.5.1 is an incremental release that contains an important fix for API 
consistency that was missed in 0.5.0 (TEZ-1571). It also adds some new APIs 
that make dynamic partition pruning code in Hive more efficient (TEZ-1447). 
Other than this there are improvements to broadcast data fetch scalability 
(TEZ-1157) and a host of bug fixes.