** BACKWARDS INCOMPATIBILITY ** NoRefs is now true by default. This means that stacktraces will _not_ store references unless you explicitly set NoRefs to a false value. This is done because it's too easy to leak memory when references are saved in stack traces.
Fixed a very odd bug where Exception::Class could mistakenly think that an exception class had been created when it really hadn't. This was only exposed with bleadperl (5.8.1-to-be), and is unlikely to affect anyone using an existing Perl version.