Fixing bugs == breaking BC? or not?

Greetings! Ok, let's review this highly abstract situation. Let's assume there is an old package in PEAR, with some old and well-known bugs. They are really bugs, 'cause they produce some weird behaviour and are not documented anywhere. Now let's assume there are some people who never bothered to fix this bugs, but made some workarounds for their own applications. Now, if we do fix these old bugs, then the applications will surely break. So a question: should such people suffer for not fixing bugs and inventing stupid workarounds or should we include "backwards compatibility" to help reproduce the bugs in fixed package?