Hive was having a newer version of httpclient and httpcore since 1.2.0 (
HIVE-9709), when compared to Hadoop 2.x versions, to be able to make use of newer apis in httpclient 4.4.
There was security issue in the older version of httpclient and httpcore that hadoop was using, and as a result moved to httpclient 4.5.2 and httpcore 4.4.4 (
As hadoop was using the older version of these libraries and they often end up earlier in the classpath, we have had bunch of difficulties in different environments with class/method not found errors.
Now, that hadoops dependencies in versions with security fix are newer and have the API that hive needs, we can be on the same version. For older versions of hadoop this version update doesn't matter as the difference is already there.