New version, database incompatible -retrain again!

[Adrian]

I use bogofilter with Claws Mail.  When I install a new version of
Claws and presumably bogofilter/Berkeley DB is upgraded as a result, the
database (wordlist.db) becomes incompatible and I'm asked to start
retraining from scratch.

If I thought about it in advance, I could dump the wordlist to text and
reload it into the new database, if that would work.  If I don't
remember, all I can do is keep a few thousand spams somewhere as a
training corpus.

Is there a simple solution?

Thanks, Adrian