Title: #347: Fixes related to negative cache and "root" user/group
@jhrozek: Let me answer your questions here ...
1. I've dropped the patches related to "0";
2. Thanks for the integration tests. I've gone through your patches and added them on
top of mines (with the Reviewed-by ...). So, if you want someone else to take a look at
those, feel free to ping whoever you feel the more appropriate person would be. But, IMO,
there's no need to open a new PR with those.
3. As replied in the code, we descend only into active domains because I wasn't sure
whether would be a good idea to descend also into inactive domains. I've changed that
Thanks for the review, suggestion and patches. I'll update the PR soon.
See the full comment at https://github.com/SSSD/sssd/pull/347#issuecomment-324015664