Description of problem:
ipa-client-install calls "authselect select sssd --force" at uninstall time
before restoring user-nsswitch.conf
user-nsswitch.conf still contains the sudoers line so nsswitch.conf is not
identical post-uninstall to previous state.


Version-Release number of selected component (if applicable):
freeipa-4.8.1-1.fc30

How reproducible:
Always


Steps to Reproduce:
0. grep sudoers /etc/nsswitch.conf => Nothing
1. ipa-client-install (...) -U
2. ipa-client-install --uninstall -U
3. grep sudoers /etc/nsswitch.conf

Actual results:
sudoers: files sss

Expected results:
Nothing

Additional info:
This is visible by setting a breakpoint:
* in ipaplatform/redhat/authconfig.py::RedHatAuthSelect::unconfigure()
* before ipautil.run(cmd)
Run ipa-client-install --uninstall
and when Pdb stops execution, examine the content of user-nsswitch.conf.