Best way to retire old code for unsupported database versions

Hi all,

I wanted to get opinions on how do deal with old code that clutters up the driver and is only needed for really old, outdated and unsupported versions of the database.

DBD::mysql has a lot of "#ifdef" clutter to deal with things that weren't supported in 4.0 and 4.1 (god forbid 3.x). 4.anything has long since not been supported by Oracle, Sky, Percona, etc. I don't know who might be running it, but I would love to rip out all the old code. The question then becomes: what to do about having something around that you can refer people who want to run 4.x (???!!!). Is a simple information tidbit "if you want to use xxx, you use version x.y.z version of DBD::mysql" ? What have others done about this issue? 

Thank you for your opinions and advice on this matter!

Regards,

Patrick Galbraith