Hello,

I recently stumbled on the bug where guix copy would the port 22 even
when I had specified a different one in my ~/.ssh/config file.

This bug is triggered when omitting the port in the --to= (or --from)
expression, such as in

guix copy --to=somehost bash

And where somehost exists in ~/.ssh/config, say:

Host somehost
     User someuser
     HostName someplace.somedns.net
     Port 1234

Instead of using port 1234, the port 22 would be used.  Commit
cc1dfc202f is the reason of this overriding; the attached patch 
reverts it, with a detailed explanation.

Thank you,

Maxim