WIP: scout Platform: If we have python3.5, ensure we have a python3 symlink
We don't install the default version of python3, which is python3.2 in scout, because that's rather old. Make "#!/usr/bin/env python3" and "#!/usr/bin/python3" scripts work anyway.
https://phabricator.collabora.com/T18302
Because this is conditional, it should hopefully be safe to land even before we include python3.5.
/cc @timo @denittis @jpwhiting