changing RUR to RUB in old accounts file

[Alexey]

Greetings!

I've been using GnuCash on Debian Etch box for an year. So, I created
file when it was GnuCash 1.8.x with currency RUR standed for Russian
ruble. 
However, there is still RUR in my accounts file and there isn't RUB
choice though I'm using GnuCash 2.0.5 at the moment. So, I get "Unable
to retrieve quotes for these items: CURRENCY:RUR Continue using only the
good quotes?" message as a result of "get quotes" request.
Question: Is there a possibility to change RUR to RUB everywhere in the
old accounts file ?

Thank you.