From my commit that I think fixes this bug:

    I received a report of a segfault with the following (trimmed) backtrace:
    
    0  tp_base_channel_constructed () at base-channel.c:604
    1  gabble_server_tls_channel_constructed (object=0x1619f8) at server-tls-channel.c:181
    [ g_object_new crap ]
    5  gabble_server_tls_manager_verify_async ([...]) at server-tls-manager.c:218
    6  wocky_tls_handler_verify_async ([...]) at wocky-tls-handler.c:261
    7  session_handshake_cb () at wocky-tls-connector.c:302
    
    Line 604 of base-channel.c dereferences the channel's connection for the
    first time. I infer that this is caused by the connection being invalid,
    which from reading the code in Gabble was probably caused by the
    TLSManager's connection being NULL, due to being cleared in
    connection_status_changed_cb() on DISCONNECTED to break a reference
    cycle.

I don't have a test case for this patch (see bug 23302 and bug 29799) but I have reproduced this crash, and verified that this patch fixes it.