Comment 12 for bug 1781991

Bionic verification

First, confirming the bug:
ubuntu@bionic-verification-sssd-sudo:~$ apt-cache policy libsss-sudo
libsss-sudo:
  Installed: 1.16.1-1ubuntu1.2
  Candidate: 1.16.1-1ubuntu1.2
  Version table:
 *** 1.16.1-1ubuntu1.2 500
        500 http://br.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages

$ grep ^sudoers /etc/nsswitch.conf
sudoers: files sss

Removing sss and checking again:
ubuntu@bionic-verification-sssd-sudo:~$ sudo vi /etc/nsswitch.conf
ubuntu@bionic-verification-sssd-sudo:~$ grep ^sudoers /etc/nsswitch.conf
sudoers: files

Reinstalling brings sss back to the sudoers line:
ubuntu@bionic-verification-sssd-sudo:~$ sudo apt install --reinstall libsss-sudo
Reading package lists... Done
...
Processing triggers for libc-bin (2.27-3ubuntu1) ...
ubuntu@bionic-verification-sssd-sudo:~$ grep ^sudoers /etc/nsswitch.conf
sudoers: files sss

Now, prior to the upgrade to the package in proposed, removing the sss bit again:
ubuntu@bionic-verification-sssd-sudo:~$ sudo vi /etc/nsswitch.conf
ubuntu@bionic-verification-sssd-sudo:~$ grep ^sudoers /etc/nsswitch.conf
sudoers: files

ubuntu@bionic-verification-sssd-sudo:~$ sudo apt install libsss-sudo
Reading package lists... Done
...
ubuntu@bionic-verification-sssd-sudo:~$ grep ^sudoers /etc/nsswitch.conf
sudoers: files

"sss" is not back, confirming the fix.
ubuntu@bionic-verification-sssd-sudo:~$ apt-cache policy libsss-sudo
libsss-sudo:
  Installed: 1.16.1-1ubuntu1.3
  Candidate: 1.16.1-1ubuntu1.3
  Version table:
 *** 1.16.1-1ubuntu1.3 500
        500 http://br.archive.ubuntu.com/ubuntu bionic-proposed/main amd64 Packages

But it's again placed there on a fresh install:
ubuntu@bionic-verification-sssd-sudo:~$ sudo apt purge libsss-sudo -y
Reading package lists... Done
Building dependency tree
...
ubuntu@bionic-verification-sssd-sudo:~$ grep ^sudoers /etc/nsswitch.conf
ubuntu@bionic-verification-sssd-sudo:~$ sudo apt install libsss-sudo
Reading package lists... Done
Building dependency tree
...
ubuntu@bionic-verification-sssd-sudo:~$ grep ^sudoers /etc/nsswitch.conf
sudoers: files sss

Bionic verification succeeded.