Added fix for codeplex 192

Author: ras0219-msft

Release/include/cpprest/http_listener.h

@@ -139,6 +139,7 @@ class http_listener_impl
 
     http_listener_impl()
         : m_closed(true)
+        , m_close_task(pplx::task_from_result())
     {
     }
 
@@ -176,6 +177,7 @@ class http_listener_impl
 
     // Used to record that the listener is closed.
     bool m_closed;
+    pplx::task<void> m_close_task;
 };
 
 } // namespace details
@@ -315,4 +317,4 @@ class http_listener
 } // namespace http
 } // namespace web
 
-#endif  /* _CASA_HTTP_LISTENER_H */
+#endif  /* _CASA_HTTP_LISTENER_H */

Release/src/http/listener/http_listener.cpp

@@ -131,10 +131,12 @@ pplx::task<void> details::http_listener_impl::close()
 {
     // Do nothing if the close operation was already attempted
     // Not thread safe.
-    if (m_closed) return pplx::task_from_result();
+    // Note: Return the previous close task
+    if (m_closed) return m_close_task;
 
     m_closed = true;
-    return web::http::experimental::details::http_server_api::unregister_listener(this);
+    m_close_task = web::http::experimental::details::http_server_api::unregister_listener(this);
+    return m_close_task;
 }
 
 void details::http_listener_impl::handle_request(http_request msg)