This was caused by using jack_port_get_connections() which will
not return the correct status for ports owned by another JACK
client. Because of the potential for deadlock by calling
jack_port_get_all_connections(), an extra argument was added
to several PortEngine:: API calls to specify whether the call
is in a process-callback context, which defaults to true.
The only place where false is passed is within the GlobalPortMatrix
when we need to determine whether two non-ardour ports are
connected.
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