n3 parser doesn't understand 'true'

[drewp]

In [15]: g = Graph()
In [16]: g.parse(StringInputSource("<x> <y> true ."), format="n3")
In [17]: list(g.triples((None,None,None)))
Out[17]:
[(rdflib.URIRef('file:///home/drewp/dl/rdflib-trunk/build/lib.linux-i686-2.5/x'),
  rdflib.URIRef('file:///home/drewp/dl/rdflib-trunk/build/lib.linux-i686-2.5/y'),
  rdflib.URIRef('file:///home/drewp/dl/rdflib-trunk/build/lib.linux-i686-2.5/#true'))]

That object should be "true"^^<http://www.w3.org/2001/XMLSchema#boolean>. It seems like this worked in the past, but I could be misremembering.