But don't break 3.x compatibility

Author: connor4312

lib/parsers.js

@@ -78,10 +78,10 @@ module.exports.parseRequest = function parseRequest(req, kwargs) {
     // host:
     //
     //   node: req.headers.host
-    //   express: req.hostname
+    //   express: req.hostname in > 4 and req.host in < 4
     //   koa: req.host
     //
-    var host = req.hostname || headers.host || '<no host>';
+    var host = req.host || req.hostname || headers.host || '<no host>';
 
     // protocol:
     //

test/raven.parsers.js

@@ -113,6 +113,18 @@ describe('raven.parsers', function(){
         parsed['request'].url.should.equal('http://mattrobenolt.com/some/path?key=value');
       });
 
+      it('should detect host via deprecated `req.host`', function(){
+        var mockReq = {
+          method: 'GET',
+          host: 'mattrobenolt.com',
+          url: '/some/path?key=value'
+        };
+
+        var parsed = raven.parsers.parseRequest(mockReq);
+
+        parsed['request'].url.should.equal('http://mattrobenolt.com/some/path?key=value');
+      });
+
       it('should detect host via `req.header.host`', function(){
         var mockReq = {
           method: 'GET',