in poplib, limit maximum line length that we read from the network (closes #16041)

Patch from Berker Peksag.
diff --git a/Misc/NEWS b/Misc/NEWS
index 01f23ef..cee5b85 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -10,6 +10,9 @@
 Library
 -------
 
+- Issue #16041: In poplib, limit maximum line length read from the server to
+  prevent CVE-2013-1752.
+
 - Issue #22960: Add a context argument to xmlrpclib.ServerProxy.