user should be able to resolve cloned body before original body

lib/body.js

@@ -205,7 +205,7 @@ Body.prototype._convert = function(encoding) {
  * @return  Mixed
  */
 Body.prototype._clone = function(instance) {
-	var pass;
+	var p1, p2;
 	var body = instance.body;
 
 	// don't allow cloning a used body
@@ -216,9 +216,14 @@ Body.prototype._clone = function(instance) {
 	// check that body is a stream and not form-data object
 	// note: we can't clone the form-data object without having it as a dependency
 	if (bodyStream(body) && typeof body.getBoundary !== 'function') {
-		pass = new PassThrough();
-		body.pipe(pass);
-		body = pass;
+		// tee instance body
+		p1 = new PassThrough();
+		p2 = new PassThrough();
+		body.pipe(p1);
+		body.pipe(p2);
+		// set instance body to teed body and return the other teed body
+		instance.body = p1;
+		body = p2;
 	}
 
 	return body;

test/test.js

@@ -939,6 +939,19 @@ describe('node-fetch', function() {
 		});
 	});
 
+	it('should allow cloning a json response, first log as text response, then return json object', function() {
+		url = base + '/json';
+		return fetch(url).then(function(res) {
+			var r1 = res.clone();
+			return r1.text().then(function(result) {
+				expect(result).to.equal('{"name":"value"}');
+				return res.json().then(function(result) {
+					expect(result).to.deep.equal({name: 'value'});
+				});
+			});
+		});
+	});
+
 	it('should not allow cloning a response after its been used', function() {
 		url = base + '/hello';
 		return fetch(url).then(function(res) {