Another "Limit by resource" test case

Dear all,

While chasing a bug in RDF::Query, I found that there was a case the current 
suite didn't catch, so I created a test case for it. I hope it can be 
accepted in the test suite. It concerns the "Limit by Resource" case where 
the query contains an OPTIONAL, and additionally there are triples in the 
data where there are more than one object for the same subject-predicate 
pair.

I have also checked this against ARQ 2.8.7, which behaves as expected. 

Please find attached a patch to subquery/manifest.ttl as well as 
sq14.ttl containing test data
sq14.rq with the query and 
sq14-out.ttl with the expected output

Best,

Kjetil
-- 
Kjetil Kjernsmo
PhD Research Fellow, University of Oslo, Norway
Semantic Web / SPARQL Query Federation
kjekje@ifi.uio.no              http://www.kjetil.kjernsmo.net/