bug#41116: Guix deploy fails with new version of Herd

[Alex Sassmannshausen]

Hello,

I maintain a number of servers using Guix deploy.  It seems that the
recent upgrade to Herd in Guix, and specifically commit
4c0cc7bed3de2c0e2d3a6e95b88693941e839eec might have introduced a bug.

>From my testing, guix deploy currently consistently fails with:
-----------------8<----------------------------->8-------------------
ice-9/boot-9.scm:1667:16: In procedure raise-exception:
ERROR:
  1. &inferior-exception:
      arguments: (srfi-34 #<inferior-object #<condition &action-exception-error 
[service: root action: eval key: keyword-argument-error args: ("#<procedure 
7fe24816e240 at shepherd/service.scm:903:4 (command #:key user group directory 
environment-variables pid-file pid-file-timeout log-file) | (program . 
program-args)>" "Unrecognized keyword" () (#:file-creation-mask))] 
7eff2bd7be00>>)
      inferior: #f
      stack: ()
-----------------8<----------------------------->8-------------------

A workaround is to build the system configuration locally on the target
server, then to reconfigure.  It will still error at the same place, but
at this point, after restarting the server, the new version of Herd will
be running and both deploy and reconfigure will work.

I don't know what a good solution to this could be, but it may be
something we need to consider in future development of Herd.

Best wishes,

Alex