Issue #3523 has been updated by Usaku NAKAMURA.

Status changed from Open to Assigned
Assigned to set to Usaku NAKAMURA

I'm tracking this ticket now.
Thank you, Bill! (and of course, Luis and Endoh-san!)

Now I'm doubting that the occasion is that SEH frame is not replaced
when the stack is replaced with fiber switch. 
The implementation of Thread of 1.8 has this replacement, but it
seems to have been forgotten in Fiber of 1.9.2...

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http://redmine.ruby-lang.org/issues/show/3523

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http://redmine.ruby-lang.org