custom keyword expansion

I'm playing around with the new custom keyword expansion.

I would like to create a keyword like:

SAL-EAGLE="/><attribute%_name="BRD-SVN-REV"%_value="%r"/><attribute%_name="dummy"%_value="

Problem is, that as soon as I incorporate a '=' character in my
definition, keyword expansion for that keyword stops working.

I this a bug or a feature 8-)

Could that be fixed/changed? For instance by defining %= similar to %_

The goal is to expand

        <attribute name="SAL" value="SAL-EAGLE:$">

to

        <attribute name="SAL" value="SAL-EAGLE:"/><attribute
name="BRD-SVN-REV" value="1234"/><attribute name="dummy" value=" $">

I anyone is interested in why I want to do such obscure things, just
ask and I try to explain 8-)

And last but not least: could that be incorporated into the 1.8
release?
Pretty, pretty please.

-- 
Lorenz