WIP: Host header is not sanitised by haproxy:
  curl -vk --header 'Host: 10.0.11.117:2150/unit_test_0/VirtualHostRoot/vh_unit_test_0/?' https://10.0.11.117:2150/unit_test_0/vincent/

Instead, use the requests' Host header.
This allows accessing the balancer under any name, including ones not
expected by the backend.