Infinite loop when accessing statements or graphs of a Sesame repository.

[kbogtob]

I can't get the contexts used inside a Sesame repository anymore. It loops infinitely until the stack level is too deep and it raises an error. It does the same when I try to list the statements using '#each_statement".

The code to trigger this behavior is pretty simple:

server = RDF::Sesame::Server.new(db_url)
repository = server.repository(repository_name')

# either this
repository.each_statement do |s| # <= each starts the infinite loop 
  puts s.inspect
end

# or this
puts repository.graph_names.inspect

I'm pushing a PR in a few minutes, I'll reference this issue.