Server insists on wrong hostname

[Christian Alge]

Thanks all of you. You made me realise my stupidity. The issue was
caused by the fact that I mount another filesystem over the /etc
directory during boot time (I know that this is dirty as hell, but it
just has to make do for legacy reasons at the moment). Therefore the
config that was read on boot is not visible on the running system.
Changing the config on the boot file system did the trick (and helped me
solve some other problems as well). Cheers.