The version of pkg in the 2015Q4 quarterly branch is 1.6.1 while the current version 1.6.2 contains important bugfixes while not introducing other big changes. In my opinion, 2015Q4 should receive the 1.6.2 update.
To be more specific, the changes made to ports-mgmt/pkg in revision r402334 should be merged into the quarterly branch. Why? The release is contains nothing but bugfixes [1]. And, while not in the official changelog, it apparently resolves issues I had with repositories not updating under certain conditions [2]. [1] http://www.freshports.org/commit.php?category=ports-mgmt&port=pkg&files=yes&message_id=201511232156.tANLuETt033816@repo.freebsd.org [2] https://lists.freebsd.org/pipermail/freebsd-pkg/2015-November/001376.html