FC3: spamassassin ignoring user prefs

[Brian Mury]

After upgrading to FC3, spamassassin seems to be ignoring the user prefs
file (~/.spamassassin/user_prefs). I have it set to not rewrite the
subject line, but it does so anyway.

If I delete the user_prefs file, spamassassin recreates it with default
values, so I'm confident that I am editing the correct file. 

This worked fine before I upgraded to FC3.

Any ideas?