Bug with bind and initBindings

[gromgull]

My fix to #294 wasn't perfect:

from rdflib import Graph
from rdflib.namespace import Namespace

n=Namespace('urn:')
g=Graph()

g.add((n.x, n.p, n.o))
g.add((n.y, n.p, n.o))

list(g.query('select ?v1 ?v2 where { ?v1 <urn:p> <urn:o> . BIND (STR(?v1) as ?v2)} '))
# [(rdflib.term.URIRef(u'urn:y'), rdflib.term.Literal(u'urn:y')),
# (rdflib.term.URIRef(u'urn:x'), rdflib.term.Literal(u'urn:x'))]

list(g.query('select ?v1 ?v2 where { ?v1 <urn:p> <urn:o> . BIND (STR(?v1) as ?v2)} ', initBindings={'v1':n.x}))
# [(rdflib.term.URIRef(u'urn:x'), None)]

If the initBound term is used in a bind, it doesn't work ... this worked before the fix to #294

[gromgull]

I am a moron. I tested the version before my fix. Nevermind.