client terminates a connection shortly after publishing a message

[traut]

I'm seeing strange behaviour: shortly after publishing a message, client dies with connection timed out (waiting for :PINGRESP).
My code is very similar to the example provided in READE.md, with one difference -- I call mqtt:publish from a thread (via bordeaux-threads). If I setup the code to just listen for a connection (in an event loop), I can consume messages and in mosquitto log I see messages like:

1515795903: Received PINGREQ from cl-mqtt
1515795903: Sending PINGRESP to cl-mqtt

But shortly after I publish anything, I get:

connection timed out (waiting for :PINGRESP)

and server logs:

1515795988: Socket error on client cl-mqtt, disconnecting.

I counted PINGREQ/PINGRESP in the server's log file and I do not see any un-answered requests. It seems cl-mqtt never sends PINGREQ but expectes PINGRESP. Any ideas?

my setup:

• cl-mqtt, master branch
• mosquitto mqtt server