Ruby

=begin
When using a selection criterion as follows:

xmldoc.elements.each("descendant::node()[(local-name()='link' or local-name()='a') and @rel='sub']")

It gives:

/usr/lib/ruby/1.9.1/rexml/xpath_parser.rb:437:in expr': undefined method inject' for true:TrueClass (NoMethodError)

But when leaving out the parentheses around two two local-name functions, it works fine.

It also worked fine on Ruby 1.8.
=end