[Spambayes] Strip Subject of Non-alpha

[Tim Peters]

[Skip Montanaro]
> ...
> I suppose I could check it in, though it's not clear that for the
> fairly small number of these sort of messages I receive that it makes
> much difference (though perhaps my code modification has a bug
> someone else could spot).  I never got overwhelming encouragement for
> my ideas about how to add experimental extensions to the CVS
> repository.

Probably because it came attached to such a weak change <wink>.  Really, a
few people tested it and it didn't seem to matter either way.  I left it on
for a month, then took it out again, and scores barely budged.  No saved
message changed classification as a result.

Experimental extensions are fine by me, and you proposed a decent scheme for
putting them in.  The downside is that every piece of code complicates the
whole, and I really don't know why you'd *want* to check in a gimmick that
made no real difference to anyone who tried it (if I remember all the
reports correctly -- maybe not).  Hoping someone might find a bug in it
isn't a good enough reason:  I'm sure you looked (as I did) at specific
before-and-after Subject lines to verify that it worked as intended.  We're
carrying around too much unused code already (e.g., extract_dow and
generate_time_buckets generated some curious statistics at the time they
were added, but, IIRC, they didn't make any bottom-line difference to
anyone's testing results).