Before, it was only possible to test commits that are
on Github (pull request or merged). Now, changes can be
tested locally too.
This introduces the risk that a release could be built
containing uncommitted changes which by definition breaks
deterministic builds. Fortunately, this will always be
detected because the version string is created using
`git describe --tags --dirty`.
Also, retire $TARGET variable because it decouples the
build scripts from the commit revision to be built. This
is a problem for deterministic builds.
