Guys Thanks for taking the trouble to send something more concrete about how to reproduce the problem.
I have found the bug, and just committed the fix. The next snapshots will have it in, so please test, and help us make sure there are no side effects! Finally, to the person who said there are plenty of "reference implementations", it seems that NetBSD has the same bug. There will always be bugs. With good bug reports (ideally to the right places!) we can track things down and fix them. Tom