Slash lost with parent nodes

[pulver]

The following code

require 'rexml'

parsed = REXML::Parsers::XPathParser.new.parse '/a/b/..'
puts "#{parsed}"
puts ""
appreviated = REXML::Parsers::XPathParser.new.abbreviate parsed
puts "#{appreviated}"

outputs

[:document, :child, :qname, "", "a", :child, :qname, "", "b", :parent, :node]

/a/b..

The expected output of abbreviate parsed is /a/b/...

I'm not sure if the problem is with parse, abbreviate, or both.

Same problem with :self node: /a/b/..