package.use should support comments, like #. I needed to add some comments to
lines, in order to know, why I enabled/disabled a USE flag, but # causes
--- Invalid atom in /etc/portage/package.use: #
comments work just fine for me:
# head /etc/portage/package.use
that's strange, I've changed comments little bit and now it's ok. Unfortunately,
I can't find out how to get this error message again...