We almost never to feature backports. But I think it would be really useful to backport support for newer Hive versions to the 1.4 branch, for the following reasons:
1. It blocks a large number of users from using Hive support.
2. It's a "relatively" small set of patches, since most of the heavy lifting was done in Spark 1.4.0's classloader refactoring.
3. Some distributions have already done this, with success.