tl;dr: internal is now lib; scripts are under script. You’ll need to rebase any open pull request that touches internal / lib.
We’ve started building stuff with the latest release candidate of Go 1.5. As part of this we noted that the previous decision to have all internal packages under internal wasn’t super smart as they are not in fact internal – many are used by the discovery server, the CLI utility and so in as well. The new Go compiler actually enforces internal import paths so these builds failed. To fix that we’ve renamed internal to lib for the time being.
I also tired of the mess of scripts at the top level and under cmd and moved these to a new script directory. This probably doesn’t affect you very much unless you run a build server that uses these scripts. The usual build.sh / build.go behave as before.