Hello,

During 'guix build -s aarch64-linux dolphin' on Berlin, I got this crash:

--8<---------------cut here---------------start------------->8---
building /gnu/store/87655bh9rqcr29qasl1c4yj3skmxkyiz-kfilemetadata-5.70.0.drv...
process 12989 acquired build slot '/var/guix/offload/overdrive1.guixsd.org:52522/1'
process 12989 acquired build slot '/var/guix/offload/dover.guix.info:9023/1'
process 12989 acquired build slot '/var/guix/offload/141.80.167.167:22/0'
process 12989 acquired build slot '/var/guix/offload/141.80.167.163:22/0'
process 12989 acquired build slot '/var/guix/offload/localhost:2223/1'
process 12989 acquired build slot '/var/guix/offload/141.80.167.168:22/0'
process 12989 acquired build slot '/var/guix/offload/141.80.167.173:22/0'
process 12989 acquired build slot '/var/guix/offload/141.80.167.176:22/0'
process 12989 acquired build slot '/var/guix/offload/localhost:2222/0'
process 12989 acquired build slot '/var/guix/offload/141.80.167.165:22/0'
process 12989 acquired build slot '/var/guix/offload/141.80.167.169:22/0'
process 12989 acquired build slot '/var/guix/offload/141.80.167.181:22/0'
process 12989 acquired build slot '/var/guix/offload/141.80.167.170:22/0'
process 12989 acquired build slot '/var/guix/offload/141.80.167.174:22/0'
process 12989 acquired build slot '/var/guix/offload/141.80.167.180:22/0'
process 12989 acquired build slot '/var/guix/offload/141.80.167.161:22/0'
Backtrace:
In ice-9/boot-9.scm:
  1736:10  5 (with-exception-handler _ _ #:unwind? _ # _)
In unknown file:
           4 (apply-smob/0 #<thunk 7f3344d296c0>)
In ice-9/boot-9.scm:
    718:2  3 (call-with-prompt _ _ #<procedure default-prompt-handle…>)
In ice-9/eval.scm:
    619:8  2 (_ #(#(#<directory (guile-user) 7f3344933f00>)))
In guix/ui.scm:
  1936:12  1 (run-guix-command _ . _)
In guix/scripts/offload.scm:
   742:22  0 (guix-offload . _)

guix/scripts/offload.scm:742:22: In procedure guix-offload:
Throw to key `match-error' with args `("match" "no matching pattern" #<eof>)'.
guix build: error: unexpected EOF reading a line
--8<---------------cut here---------------end--------------->8---

Which is strange because guix/scripts/offload.scm:742 is wrapped in a
(unless (eof-object? ...)) block.

When this happens, the build command terminates, along with any other
builds that it had started concurrently.  Builds from other clients
were unaffected, of course.

I have also seen this occur on my personal offloading setup once every
blue moon, but don't know what could have caused it.