bug#26407: test.dicod fails after ~20 hours of failed connection attempts

[Mark H Weaver]

Recently, test.dicod has started failing after taking ~20 hours of
build-slot time, mostly filled with "Connection refused" errors:

  https://hydra.gnu.org/job/gnu/master/test.dicod.x86_64-linux

Here's a build that recently failed after 20 hours:

  https://hydra.gnu.org/build/1974589

and here's one that, as of the time of this writing, is currently 14
hours into the build, and stuck in the same "Connection refused" loop:

  https://hydra.gnu.org/build/1974709

      Mark