extended-tests: lock the board

A possible solution to Gitea issue #8.

main.nix

@@ -92,6 +92,12 @@ in
       cp /opt/hydra_id_rsa.pub $HOME/.ssh/id_rsa.pub
       echo "rpi-1,192.168.1.188 ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIMc7waNkP2HjL5Eo94evoxJhC8CbYj4i2n1THe5TPIR3" > $HOME/.ssh/known_hosts
       chmod 600 $HOME/.ssh/id_rsa
+      mkfifo /tmp/lockctl
+
+      ( cat /tmp/lockctl ) | ssh rpi-1 'flock /tmp/board_lock-kc705-1 -c "echo Ok; cat"' | (
+        # Read "Ok" line when remote successfully locked
+        read LOCK_OK
+
         artiq_flash -t kc705 -H rpi-1
         sleep 15
         # ping: socket: Operation not permitted
@@ -103,6 +109,10 @@ in
 
         ${windowsRunner { testCommand = "set ARTIQ_ROOT=%cd%\\anaconda\\envs\\artiq-env\\Lib\\site-packages\\artiq\\examples\\kc705_nist_clock&&python -m unittest discover -v artiq.test.coredevice"; }}/bin/run.sh
 
+        # End remote flock via FIFO
+        echo > /tmp/lockctl
+      )
+
       mkdir $out
       cp ${generatedNix}/pkgs/artiq-version.nix $out/passed
       '';