Bug#914541: [libpam-modules-bin] unix_chkpwd should be SUID instead of SGID, otherwise kscreen_locker does not work

[hg42]

As a workaround, I created a file /etc/apt/apt.conf.d/99hg-fix-unix_chkpwd
# https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=914541
DPkg::Post-Invoke { "/usr/bin/stat -c '%n %a %U %G' /sbin/unix\_chkpwd ; chmod 
4755 /sbin/unix\_chkpwd ; /usr/bin/stat -c '%n %a %U %G' /sbin/unix\_chkpwd"; };

which ensures the necessary permissions after each update