Second try

while we're waiting on nodejs/node#493

package.json

@@ -23,6 +23,7 @@
     },
     "main"            : "index.js",
     "devDependencies" : {
+        "detect-engine" : "~1.0.2",
         "express"       : "~4.8.6",
         "mocha"         : "~1.21.4",
         "passport"      : "~0.2.0",

test/basic.js

@@ -1,4 +1,5 @@
-var lib     = require('./lib'),
+var engine  = require('detect-engine'),
+    lib     = require('./lib'),
     mocha   = require('mocha'),
     request = require('request'),
     should  = require('should');
@@ -23,9 +24,8 @@ describe('request-debug', function() {
     });
 
     function maybeTransferEncodingChunked(obj) {
-        // io.js has major version >= 1
-        var isNode = process.versions.node.test(/^0\./);
-        if (isNode) {
+        if (engine == 'node') {
+            // Node sends 'Transfer-Encoding: chunked' here, io.js does not
             obj['transfer-encoding'] = 'chunked';
         }
         return obj;

test/lib/index.js

@@ -73,10 +73,8 @@ var fixHeader = {
         return val.replace(/^application\/x-www-form-urlencoded(; charset=utf-8)?$/, '<application/x-www-form-urlencoded>');
     },
     'content-length' : function(val, obj) {
-        // io.js has major version >= 1
-        var isNode = process.versions.node.test(/^0\./);
-        if (!isNode && obj.statusCode == 401) {
-            // io.js sends content-length here, Node.js does not
+        if (engine == 'iojs' && obj.statusCode == 401) {
+            // io.js sends content-length here, Node does not
             return null;
         }
     }