Suppress the warning in asynchat from using buffer() when running udner -3.
Naively removing the usage causes a large number of test failures, so it was
just easier to suppress the warning.
diff --git a/Lib/asynchat.py b/Lib/asynchat.py
index 8a7176d..121b467 100644
--- a/Lib/asynchat.py
+++ b/Lib/asynchat.py
@@ -49,6 +49,8 @@
 import socket
 import asyncore
 from collections import deque
+from test.test_support import catch_warning
+from warnings import filterwarnings
 
 class async_chat (asyncore.dispatcher):
     """This is an abstract class.  You must derive from this class, and add
@@ -216,7 +218,9 @@
             # handle classic producer behavior
             obs = self.ac_out_buffer_size
             try:
-                data = buffer(first, 0, obs)
+                with catch_warning(record=False):
+                    filterwarnings("ignore", ".*buffer", DeprecationWarning)
+                    data = buffer(first, 0, obs)
             except TypeError:
                 data = first.more()
                 if data: