Tornado reloads the app whenever there is a change in code. Due to this,
new connection is created to the client which also results in a new
channel. To avoid creating two channels for the queue in the RabbitMQ
broker we should close the old channel. Otherwise messages sent to the
queue will be distributed among these two channels in a round robin
scheme and we will end up losing one message since one of the channels
doesn't have an active consumer.
This commit closes the connection to the queue whenever Tornado reloads
the application using add_reload_hook().
Fixes#5824.
b4d49720b0