PaulUithol/Backbone-relational — pull request #406 by idanz (2013-10-14 08:35:59+00:00)
Title: Only nullify the keyId if we found the related model

I think this is a bug, since the comparable case of keyIds does use the related models and not the current this.related model.
For me this caused problem when I tried to set the relation to a string, expecting it to work like a non-fetched relation from the server, and saw that is made the relation not appear in the model JSON, as it does when it is set by server.