Fix for Reason-Phrase being overwritten on proxy response. (#1051)

* Fix for Reason-Phrase being overwritten on proxy response.

Calling res.writeHead has the side effect of defaulting the Reason-Phrase to default ones.  I'm using Reason-Phrase codes to sub-route api responses and they were all being reset.  This change only sets the statusMessage (Reason-Phrase) if it exists on the proxyRes and is successfully passing it through in my tests.

* Fixed spaces and bracket formatting.

lib/http-proxy/passes/web-outgoing.js

@@ -108,7 +108,10 @@ var redirectRegex = /^201|30(1|2|7|8)$/;
    * @api private
    */
   function writeStatusCode(req, res, proxyRes) {
-    res.writeHead(proxyRes.statusCode);
+    res.statusCode = proxyRes.statusCode;
+    if(proxyRes.statusMessage) {
+      res.statusMessage = proxyRes.statusMessage;
+    }
   }
 
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