Debian jessie introduced pam-auth-update, which packages call when they have
bits of common PAM configuration.

From NEWS file:

  [systemd] New class to allow systemd daemon reloads. (adamhl)

  [dns] Changes Livermore detection to use the system's primary IP
  address, instead of using a manually-set parameter. (akkornel)

  [kerberos] Automatically determine if we are in Livermore; if we are,
  place the Livermore-based KDC at the top of the list. (akkornel)

  Clients who are using the base::kerberos::dr class should immediately
  switch to using base::kerberos.  base::kerberos::dr is deprecated.

  [kerberos] Add two parameters to the base::kerberos class. The first
  is used to force the kerberos client to prefer TCP over UDP. The
  second allows one to indicate which kerberos environment to use: prod,
  test, or uat. In both cases, the defaults are such that the krb5.conf
  will continue to have the same contents as before the addition of
  these parameters.

If the system's primary IP address is in one of the two well-known Livermore
netblocks, then automatically set the Livermore-based Kerberos server as the
primary KDC.

base::kerberos::dr is now deprecated.

We know the three large IP address blocks that exist in Livermore, and we now
have an ip_in_cidr() function, so we are using that to tell if a system is in
Livermore.

This code will need updating only if the large network blocks in Livermore are
changed.