Bug#887972: exim4-config: empty strings become "empty"

[Gedalya]

Package: exim4-config
Version: 4.90-4

In line 356, update-exim4.conf turns empty variables into the string "empty".
As a result, we get things like this:

MAIN_RELAY_TO_DOMAINS=empty

which means that an email to gedalya at empty is allowed through, and that's probably not the intended behavior.

Thanks,

Gedalya