#27364: fix "incorrect" uses of escape character in the stdlib.

And most of the tools.

Patch by Emanual Barry, reviewed by me, Serhiy Storchaka, and
Martin Panter.
diff --git a/Lib/test/test_cgi.py b/Lib/test/test_cgi.py
index 1647849..6373221 100644
--- a/Lib/test/test_cgi.py
+++ b/Lib/test/test_cgi.py
@@ -148,7 +148,7 @@
     def test_escape(self):
         # cgi.escape() is deprecated.
         with warnings.catch_warnings():
-            warnings.filterwarnings('ignore', 'cgi\.escape',
+            warnings.filterwarnings('ignore', r'cgi\.escape',
                                      DeprecationWarning)
             self.assertEqual("test & string", cgi.escape("test & string"))
             self.assertEqual("&lt;test string&gt;", cgi.escape("<test string>"))