Problem: mlm_mailbox_bounded_test leaves dangling 'PUB' socket

[BHare1985]

In the mlm_mailbox_bounded.c under the function mlm_mailbox_bounded_test the following code runs:

    void *logger = zsys_socket (ZMQ_SUB, NULL, 0);
	...
    zsys_close (logger, NULL, 0);

But results in the test warning:

	[18648]dangling 'PUB' socket created at src/zsys.c:2510
	dangling sockets: cannot terminate ZMQ safely

I have narrowed it down to just those two lines. I am not sure if this is a better issue for czmq as thats where zsys_close lives and seems like it is not doing it's job properly. Using czmq 4.2.2