ddb9396743
The sockets were never interrupted or closed by the client since recent
changes to run the server from a dedicated thread (see commit
0426708544).
As a side effect, the server could never terminate properly (it was
waiting on socket blocking calls), so it was always killed by the client
after the WATCHDOG_DELAY.
Interrupt the sockets on stop to give the servera chance to terminate
property, then close them.