Help diagnosing/reporting a crash from CFUNC wait2 (via Process.wait2)

For reasons I can’t quite understand, code which used to work is not
failing from within wait2. I’m still working on how to concisely repro
it (not easy), but the ruby stack trace suggests that I contact a
bugreport page ( which now
just redirects me to redmine. Am I supposed to file this as a bug?

The few snippets from the control frame:

11: [BUG] rb_sys_fail() - errno == 0
ruby 1.9.1p0 (2009-01-30 revision 21907) [i386-darwin9.6.0]

– control frame ----------
c:0020 p:---- s:0092 b:0092 l:000091 d:000091 CFUNC :wait2

Note that I’ve actually tried this with 1.9.1p243 as well as with
1.9.2-preview1, and all consistently fail in the same way.