Try a bigger sleep to get Docker restarted

test/640_proxy_restart_reattaches_test.sh

@@ -38,7 +38,7 @@ assert_raises "proxy exec_on $HOST1 c3 $CHECK_ETHWE_UP"
 
 # Restart docker itself, using different commands for systemd- and upstart-managed.
 run_on $HOST1 sh -c "command -v systemctl >/dev/null && sudo systemctl restart docker || sudo service docker restart"
-sleep 1
+sleep 5
 check_attached
 
 end_suite