issue27202 - Exclude 2.x release notes from python3 make doctests.

Patch contributed by Jelle Zijlstra.
diff --git a/Doc/conf.py b/Doc/conf.py
index d6f20ba..114f9b6 100644
--- a/Doc/conf.py
+++ b/Doc/conf.py
@@ -36,8 +36,9 @@
 # Require Sphinx 1.2 for build.
 needs_sphinx = '1.2'
 
-# Ignore any .rst files in the venv/ directory.
-exclude_patterns = ['venv/*']
+# Ignore any .rst files in the venv/ directory, and don't attempt to run tests
+# in the 2.x release notes.
+exclude_patterns = ['venv/*', 'whatsnew/2.*.rst']
 
 
 # Options for HTML output