The brokered third-party browse e2e failed deterministically on CI. The test
bound its listener to 127.0.0.1 only, but the server brokers back the address
it observed for that client - the host's routable IP (172.17.0.2 under Docker,
10.x on a CI runner). The sharer's dial was refused, it fell back to
re-brokering, and the accept never arrived. The sibling third-party browse
tests already bind 0.0.0.0.
disconnect_with_error logged only "disconnect" and dropped the io::Error on the
floor, which is what made this invisible in the logs; it now logs the cause.
Michel de Graaf
54feb3bc5a