Snapcraft 2.15 has been released recently, but it already received a first point release, version 2.15.1, and it looks like also landed in the main software repositories of the Ubuntu 16.04 LTS (Xenial Xerus) operating system. As for the new features, we can tell you that Snapcraft 2.15 adds built tags support to the Go plugin, lets you set fine grain control of parallel building per part, as well as to set constraints when using the Python2 plugin, and permits the in tree snapcraft.yaml file to also refer to external sources.