murb reports the following error message in 0.2.3.10-alpha: ``` Dec 28 15:59:37.000 [err] _circuit_mark_for_close(): Bug: circuitlist.c:1222: _circuit_mark_for_close: Assertion ocirc->rend_data failed; aborting ``` There were no relevant notices or warnings before this message. I see several code paths which can set a circuit's purpose to `CIRCUIT_PURPOSE_C_INTRODUCING`, then mark it for close before its `rend_data` field is set; there's no way we can get rid of those paths. Time to remove this assertion.