ftp_do_more: consider DO_MORE complete when server connects back

In the case of an active connection when ftp_do_more() detects that the
server has connected back, it must make sure to mark it as complete so
that the multi_runsingle() function will detect this and move on to the
next state.

Bug: http://curl.haxx.se/mail/lib-2013-07/0115.html
Reported-by: Clemens Gruber

lib/ftp.c

@@ -3748,6 +3748,9 @@ static CURLcode ftp_do_more(struct connectdata *conn, bool *complete)
 
         if(result)
           return result;
+
+        *complete = TRUE; /* this state is now complete when the server has
+                             connected back to us */
       }
     }
     else if(data->set.upload) {