http: prevent aborted event when request is complete

When socket is closed on a response for a request that is being piped to a stream
there is a condition where aborted event will be fired to http client when socket is
closing and the incomingMessage stream is still set to readable.

We need a check for request being complete and to only raise the 'aborted' event
on the http client if we have not yet completed reading the response from the server.

Fixes: nodejs#18756

lib/_http_client.js

@@ -321,7 +321,7 @@ function socketCloseListener() {
   var parser = socket.parser;
   if (req.res && req.res.readable) {
     // Socket closed before we emitted 'end' below.
-    req.res.emit('aborted');
+    if (!req.res.complete) req.res.emit('aborted');
     var res = req.res;
     res.on('end', function() {
       res.emit('close');