FindBoost doesn't know about Boost 1.66

Boost 1.66 is in beta, but FindBoost doesn't know about it yet (in CMake git master).

This presents a problem for third-party code (e.g. the ceph filesystem) which uses Boost (1.65) and CMake; updating Boost to a newer version can break ceph because CMake won't find Boost anymore, and/or the imported targets are no longer defined.

Is there a special reason for not defining those imported targets based on the most-recent known release, when a newer release is detected? e.g. everything defined for Boost 1.65 should be valid for Boost 1.66 as well, even if newer libraries aren't known yet. Third-party code that works with Boost 1.65 will then not be broken by a Boost upgrade, and Boost upgrades don't have to wait on CMake releases to update this module.

(On IRC someone pointed me to ${Boost_ADDITIONAL_VERSIONS}, but that doesn't fix the dependencies and imported targets problem).