The "GnuPG uses the configured keyserver" step needs to be adjusted for Stretch
We now use GnuPG v2, so network operations are delegated to dirmngr and
gpg’s stderr does not mention the keyserver being used.
We should instead parse the output of
gpg-connect-agent --dirmngr 'keyserver --hosttable' /bye (or similar).
And then, perhaps the ugly
gnupg_recv_key_res variable can go away :)
Meanwhile, I’m going to disable this step.