Sounds to me like the machine you are testing on uses systemd as its init system. Correct?
The /etc/default/ folder is a feature of SystemV init scripts and as such is not used by systemd init. It is also one of the parts that is not worked around by the Debian systemd integration. You can find discussions on that specific oddity in debian-devel [1]. The systemd alternative is to create a local .service file with custom changes like that. OR, as you found - the best solution is to put the relevant helper parameter in squid.conf so only the software using it knows the keytab location, and it can be changed per-instance if desired. I am adding a NEWS.debian section to mention this and another systemd surprise awaiting people who disabled Squid in that config file. Not sure what else we can do than warn people. Any ideas welcome. Amos [1] <https://lists.debian.org/debian-devel/2014/08/msg00603.html>
