Andreas Lehner reports the following assertion failure on 0.2.4.4-alpha ``` Oct 25 14:56:51.000 [err] update_circuit_on_cmux(): Bug: src/or/relay.c:2002: update_circuit_on_cmux: Assertion circuitmux_is_circuit_attached(cmux, circ) failed; aborting. ``` I've asked for a stack trace.