bug#22088: Non-deterministic daemon protocol errors

[Mark H Weaver]

Since updating my guix client (but not yet my server) to include the
recent commits related to the protocol update, I'm seeing these errors
non-deterministically while building things.  Retrying usually results
in success.

address@hidden:~/guix$ guix build -K openssl --cores=1
substitute: updating list of substitutes from 'http://hydra.gnu.org'... 100.0%
The following derivation will be built:
   /gnu/store/5hzf27bgygjp5ah3bfy8m0aa93yazgk3-openssl-1.0.2e.drv
guix build: error: build failed: EOF expected (protocol error?)

       Mark