RE: [gnugo-devel] gnugo 3.7.8 (seed 116584113): You stepped on a bug.

[Portela Fernando]

> ***assertion failure:
> semeai.c:215 - board[semeai_defense_target] ==
> (WHITE+BLACK-(board[dragon2[d1].origin])) near PASS***

This may happen when the OWL code comes up with inconsistent semeai
results. The most likely cause is 

> --enable-experimental-owl-ext

This option hasn't been maintained in sync with the rest of the engine
for a very (very!) long time and it's most certainly broken.
Just don't use it.

/nando