This problem happens on Debian Stretch.
192.168.122.2 - - [2017-08-29 11:40:19] "POST /longpolling/poll HTTP/1.0" 200 330 51.760627
192.168.122.2 - - [2017-08-29 11:40:26] "POST /longpolling/poll HTTP/1.0" 200 305 50.867880
192.168.122.2 - - [2017-08-29 11:40:30] "POST /longpolling/poll HTTP/1.0" 200 329 50.049836
192.168.122.2 - - [2017-08-29 11:40:31] "POST /longpolling/poll HTTP/1.0" 200 304 50.145807
Other messages go to syslog/logfile just fine.
This breaks CI/CD because runner stops and does not return.