~ $ rpm -q --scripts  nscd
preinstall scriptlet (using /bin/sh):
getent group nscd >/dev/null || /usr/sbin/groupadd -g 28 -r nscd
getent passwd nscd >/dev/null ||
  /usr/sbin/useradd -M -o -r -d / -s /sbin/nologin \
		    -c "NSCD Daemon" -u 28 -g nscd nscd
postinstall scriptlet (using /bin/sh):
%systemd_post nscd.service
preuninstall scriptlet (using /bin/sh):
%systemd_preun nscd.service
postuninstall scriptlet (using /bin/sh):
if test $1 = 0; then
  /usr/sbin/userdel nscd > /dev/null 2>&1 || :
fi
%systemd_postun_with_restart nscd.service


$ rpm -q  nscd          
nscd-2.17-13.fc19.x86_64

this make the package unable to be upgraded, without manually fiddling with it.