Why doesn't my destroy function work with data:{rev....}?

gistfile1.js

var couchDoc = Backbone.Model.extend(
    {
	idAttribute: "_id",
	save:function(attrs,options){
	    function updateRev(model,resp,status){
		model.set({_rev:status.rev,_id:status.id},{silent: true});
	    };
	    options || (options = {});
	    var model = this;
	    var success = options.success;   
	    options.success = function(resp, status, xhr){
		updateRev(model,resp,status);
		if (success){success(model, resp, status);}
	    };
	    Backbone.Model.prototype.save.call(this, attrs, options);
	},	
	//DELETE /somedatabase/some_doc?rev=1582603387 HTTP/1.0
	destroy:function(options){
	    options || (options = {});
	    var model = this;
	    //_.extend(options,{data:{rev:model.get('_rev')}}); DOESN'T WORK
	    _.extend(options,{url: model.url()+"?rev="+model.get('_rev')});
	    Backbone.Model.prototype.destroy.call(this, options);
	}
    });