Additional repository keys

[Andreas Heinlein]

Hello,

it seems I missed some change in the behaviour of adding apt keys. I
have several apt keys in the config space in packages/<CLASS>.asc. The
fai-guide says these are being added via apt-key add, and I remember it
was that way in the past.

Today I noticed with FAI 5.6, that these files seem to be copied over to
/etc/apt/trusted.gpg.d instead. This works with Debian 9, but does not
with Debian 8. The apt version in Debian 8 requires the keys to be in
binary format and have the extension .gpg. I still need to be able to
install jessie clients with a stretch nfsroot, though.

Would it be possible to patch FAI to copy over <CLASS>.gpg files as well?

Thanks,
Andreas