It seems that one request succeeds, then all others fail. From a freshly started -web container doing on import on it, I get:

[pid: 75|app: 0|req: 5/14] 81.34.125.244 () {44 vars in 801 bytes} [Thu Feb 8 17:37:50 2018] GET /1/latest-import?user_name=rob => generated 62 bytes in 5 msecs (HTTP/2.0 200) 12 headers in 598 bytes (2 switches on core 0)
[pid: 75|app: 0|req: 6/15] 81.34.125.244 () {46 vars in 827 bytes} [Thu Feb 8 17:37:52 2018] OPTIONS /1/submit-listens => generated 0 bytes in 4 msecs (HTTP/2.0 200) 8 headers in 398 bytes (0 switches on core 0)
[2018-02-08 17:37:52,683] ERROR in api_tools: Connection to rabbitmq closed while trying to publish: (-1, 'EOF')
[pid: 76|app: 0|req: 6/16] 81.34.125.244 () {50 vars in 953 bytes} [Thu Feb 8 17:37:52 2018] POST /1/submit-listens => generated 89 bytes in 254 msecs (HTTP/2.0 503) 8 headers in 436 bytes (2 switches on core 0)
[2018-02-08 17:37:53,355] ERROR in api_tools: Cannot publish to rabbitmq channel: AttributeError / 'NoneType' object has no attribute 'is_open'
[pid: 72|app: 0|req: 1/17] 81.34.125.244 () {50 vars in 953 bytes} [Thu Feb 8 17:37:53 2018] POST /1/submit-listens => generated 89 bytes in 149 msecs (HTTP/2.0 503) 8 headers in 436 bytes (2 switches on core 0)