Today, while stumbling upon this thread, I got an idea.
I ran a quick diff on the (/etc/cabal/Data/)Const.scp from the 2.5 final release versus the new one aaaand bingo:

So I deleted line 304 from the new Const.scp and restarted the server. To my own suprise, the server started without moaning and the problem was gone.
There is however a small limitation:
If you change your rates, your fix will be overwritten.
So in order to make this change permanent, you may also want to edit the /etc/cabal/templates/Const.cfg
Delete the following line:
Code:
1 0 4 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Disclaimer:
Don't consider this a fix, it's a dirty hack.
I havent really tested this so far, so I can't guarantee for stability or if the server gains self-awareness and starts eating kittens and/or users.