fix double emit on fetch()

lib/imap.js

@@ -248,13 +248,15 @@ ImapConnection.prototype.connect = function(loginCb) {
       if (indata.expect > -1) {
         if ((m = /\* (\d+) FETCH/i.exec(indata.line))
             && /^BODY\[/i.test(litType)) {
-          msg = new ImapMessage();
-          msg.seqno = parseInt(m[1], 10);
-          requests[0].msg = msg;
+          if (!requests[0].msg) {
+            msg = new ImapMessage();
+            msg.seqno = parseInt(m[1], 10);
+            requests[0].msg = msg;
+            var fetches = requests[0].fetchers[litType];
+            for (var f = 0, lenf = fetches.length; f < lenf; ++f)
+              fetches[f].emit('message', msg);
+          }
           requests[0].key = litType;
-          var fetches = requests[0].fetchers[litType];
-          for (var f = 0, lenf = fetches.length; f < lenf; ++f)
-            fetches[f].emit('message', msg);
           indata.streaming = (!RE_ISHEADER.test(litType));
           if (indata.streaming)
             indata.literals.push(indata.expect);