When I try to install the package scdaemon, it wants a different version
of gnupg-agent than what is available in the repository.
So how should I handle the following error?

 The following packages have unmet dependencies:
   scdaemon : Depends: gnupg-agent (= 2.1.18-6)
    but 2.1.18-8 is to be installed

This is on Ascii for amd64:

    $ lsb_release -rd; uname -sr;
    Description:    Devuan GNU/Linux 2.0 (ascii)
    Release:        2.0
    Linux 4.9.0-3-amd64

The system is up to date as far as APT is concerned.

/Lars