Issue #17527: Add PATCH to wsgiref.validator. Patch from Luca Sbardella.
diff --git a/Lib/wsgiref/validate.py b/Lib/wsgiref/validate.py
index 04a893d..c327812 100644
--- a/Lib/wsgiref/validate.py
+++ b/Lib/wsgiref/validate.py
@@ -329,7 +329,7 @@
 
     # @@: these need filling out:
     if environ['REQUEST_METHOD'] not in (
-        'GET', 'HEAD', 'POST', 'OPTIONS','PUT','DELETE','TRACE'):
+        'GET', 'HEAD', 'POST', 'OPTIONS', 'PATCH', 'PUT', 'DELETE', 'TRACE'):
         warnings.warn(
             "Unknown REQUEST_METHOD: %r" % environ['REQUEST_METHOD'],
             WSGIWarning)