Hello!

After reconfiguring a remote machine on latest 'master' (post recent
core-updates merge), I found that offloading to it would just "hang".

After some debugging I found that `guile --listen` failed to import
(ice-9 readline).  Installing guile-readline for the offload user did
the trick.

It would be great to make Guile fail gracefully and print a message
about readline being unavailable instead of just looping endlessly.  Or
at the very least document the requirement.