Fix return from the changes_reader_cb
Fix return from the changes_reader_cb

CouchDB's changes enumerator doesn't support stopping the read midstream
so we need to not return a tagged accumulator.

fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb