bug#61642: intermittent write_wait_fd error when updating

[Nathan Dehnel]

guix v 636b771536b95d15a2fd68b468deeebac97d6bee

substitute: updating substitutes from
'https://substitutes.nonguix.org'...   0.0%Backtrace:
substitute: In ice-9/boot-9.scm:
substitute:   1752:10 17 (with-exception-handler _ _ #:unwind? _ # _)
substitute: In unknown file:
substitute:           16 (apply-smob/0 #<thunk 7fcb3af102a0>)
substitute: In ice-9/boot-9.scm:
substitute:     724:2 15 (call-with-prompt _ _ #<procedure
default-prompt-handle…>)
substitute: In ice-9/eval.scm:
substitute:     619:8 14 (_ #(#(#<directory (guile-user) 7fcb3af15c80>)))
substitute: In guix/ui.scm:
substitute:    2279:7 13 (run-guix . _)
substitute:   2242:10 12 (run-guix-command _ . _)
substitute: In ice-9/boot-9.scm:
substitute:   1752:10 11 (with-exception-handler _ _ #:unwind? _ # _)
substitute:   1752:10 10 (with-exception-handler _ _ #:unwind? _ # _)
substitute: In guix/scripts/substitute.scm:
substitute:    844:18  9 (_)
substitute:    348:26  8 (process-query #<output: file 4> _
#:cache-urls _ #:acl _)
substitute: In guix/substitutes.scm:
substitute:    382:27  7 (lookup-narinfos/diverse _ _ #<procedure
7fcb38ce3760 …> …)
substitute:    339:31  6 (lookup-narinfos
"https://substitutes.nonguix.org"; _ # _ …)
substitute:    262:26  5 (fetch-narinfos _ _ #:open-connection _ # _)
substitute: In ice-9/boot-9.scm:
substitute:   1685:16  4 (raise-exception _ #:continuable? _)
substitute:   1685:16  3 (raise-exception _ #:continuable? _)
substitute:   1780:13  2 (_ #<&compound-exception components:
(#<&error> #<&orig…>)
substitute:   1685:16  1 (raise-exception _ #:continuable? _)
substitute:   1685:16  0 (raise-exception _ #:continuable? _)
substitute:
substitute: ice-9/boot-9.scm:1685:16: In procedure raise-exception:
substitute: In procedure write_wait_fd: unimplemented
guix upgrade: error:
`/gnu/store/263q5qr1dcs4j7vxqk10gilv5py06r49-guix-1.4.0-3.d5fece6/bin/guix
substitute' died unexpectedly