Investigate pipeline system test failure

Job #1209225 failed for 37e4eb53:

FAIL: pipelined
7719===============
7720S:pipelined:2020-10-07T23:20:20+0000
7721T:pipelined:1:A
7722A:pipelined:System test pipelined
7723I:pipelined:PORTS:8339,8340,8341,8342,8343,8344,8345,8346,8347,8348
7724I:pipelined:starting servers
7725I:pipelined:check pipelined TCP queries
7726I:pipelined:check pipelined TCP queries using mdig
7727response failed with unexpected error
77283d2
7729< b.examplea. 10.0.1.2
77307d5
7731< d.examplea. 10.0.1.4
7732I:pipelined:diff sorted failed
7733I:pipelined:failed
7734I:pipelined:check keep-response-order
7735rndc: connect failed: 10.53.0.4#8348: connection refused
7736unix/socket.c:4772: connect(10.53.0.4#8339) 103/Software caused connection abort
7737I:dns_request_create: unexpected error
77381,8d0
7739< e.examplea. 10.0.1.5
7740< e.exampleb. 10.0.2.5
7741< f.examplea. 10.0.1.6
7742< f.exampleb. 10.0.2.6
7743< g.examplea. 10.0.1.7
7744< g.exampleb. 10.0.2.7
7745< h.examplea. 10.0.1.8
7746< h.exampleb. 10.0.2.8
7747I:pipelined:failed
7748I:pipelined:check keep-response-order using mdig
7749rndc: connect failed: 10.53.0.4#8348: connection refused
7750unix/socket.c:4772: connect(10.53.0.4#8339) 103/Software caused connection abort
7751mdig: dns_request_createvia4 failed with unexpected error
77521,8d0
7753< e.examplea. 10.0.1.5
7754< e.exampleb. 10.0.2.5
7755< f.examplea. 10.0.1.6
7756< f.exampleb. 10.0.2.6
7757< g.examplea. 10.0.1.7
7758< g.exampleb. 10.0.2.7
7759< h.examplea. 10.0.1.8
7760< h.exampleb. 10.0.2.8
7761I:pipelined:failed
7762I:pipelined:check mdig -4 -6
7763rndc: connect failed: 10.53.0.4#8348: connection refused
7764I:pipelined:check mdig -4 with an IPv6 server address
7765I:pipelined:exit status: 3
7766I:pipelined:stopping servers
7767I:pipelined:ns4 died before a SIGTERM was sent
7768I:pipelined:stopping servers failed
7769I:pipelined:1 assertion failure(s) found
7770R:pipelined:FAIL
7771E:pipelined:2020-10-07T23:20:43+0000
7772FAIL pipelined (exit status: 1)