[ZODB-Dev] preventing a transaction from committing within appcode

[Tim Peters]

IIRC, the last time this general area came up was:

    "API for dooming a transaction for ZODB 3.3"
    http://mail.zope.org/pipermail/zodb-dev/2004-January/006414.html

After growing some complications, it seemed to fizzle out.  It's still
relevant, though, because the current thread seems to be retracing its steps
<wink>.