Issue #10883: Fix socket leaks in urllib.request.

* ftpwrapper now uses reference counting to ensure that the underlying socket
  is closed when the ftpwrapper object is no longer in use
* ftplib.FTP.ntransfercmd() now closes the socket if an error occurs

Initial patch by Victor Stinner.
diff --git a/Misc/NEWS b/Misc/NEWS
index 4bea4ea..7448838 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -37,6 +37,8 @@
 Library
 -------
 
+- Issue #10883: Fix socket leaks in urllib.request when using FTP.
+
 - Issue #12592: Make Python build on OpenBSD 5 (and future major releases).
 
 - Issue #12372: POSIX semaphores are broken on AIX: don't use them.