From reading the mailing lists on this, it looks like OpenBSD detects overlapping memcpy regions, considers it a bug, and segfaults the offending program to prevent unpredictable behavior.
*Of course* it had to be OpenBSD. What else? Thanks for the report. I'm going to check the memcpy's, see if there's one that overlaps. Wow, it could even be the first time OpenBSD's quirkiness is actually *useful* to the developer. -- Laurent