[Test case] disjunctive information from unsafe use of built-ins

Another nasty test case for the case of unsafe use of variables:

http://www.w3.org/2005/rules/wiki/Disjunctive_Information_from_Unsafe_Builtins
-- 
                         debruijn@inf.unibz.it

Jos de Bruijn,        http://www.debruijn.net/
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