Add changelog entry for 642468f

Author: mnaberez

CHANGES.rst

@@ -5,6 +5,11 @@
   file descriptor under some circumstances, which caused excessive
   polling, resulting in higher CPU usage.  Patch by aftersnow.
 
+- Fixed a bug where restarting ``supervisord`` may have failed with
+  the message ``Error: Another program is already listening
+  on a port that one of our HTTP servers is configured to use.``
+  if an HTTP request was made during restart.  Patch by Julien Le Cléach.
+
 - On Python 3.8 and later, ``setuptools`` is no longer a runtime
   dependency.  Patch by Ofek Lev.