MySQL-Sandbox is a great tool for testing a new release, and in fact this is what I do when a new MySQL tarball becomes available. I don't think many people are aware of the full testing capabilities of the sandbox, though.
It had been in the making for long time. Google announced that Google Code would be closing, and since then the Continuent team has been hard at work to handle the transition. You can guess it: this operation would have been quicker if it had been done by a small company like we were one year ago, but being part of a large corporation introduces some constraints that have affected our schedule.
The latest MySQL Sandbox, version 3.0.66 is out. It has a few new features (as always, when I find myself doing the same thing many times, I script it) and improved support for latest releases of MySQL. You can now install, among other versions, MySQL 5.7.8 and MariaDB 10.1.x