Issue #28435: Avoid no_proxy environment variable interfering with tests

Patch by Piotr Szczepaniak.
diff --git a/Lib/test/test_urllib2_localnet.py b/Lib/test/test_urllib2_localnet.py
index 51a95dc..9199cb9 100644
--- a/Lib/test/test_urllib2_localnet.py
+++ b/Lib/test/test_urllib2_localnet.py
@@ -329,6 +329,14 @@
 
     def setUp(self):
         super(ProxyAuthTests, self).setUp()
+        # Ignore proxy bypass settings in the environment.
+        def restore_environ(old_environ):
+            os.environ.clear()
+            os.environ.update(old_environ)
+        self.addCleanup(restore_environ, os.environ.copy())
+        os.environ['NO_PROXY'] = ''
+        os.environ['no_proxy'] = ''
+
         self.digest_auth_handler = DigestAuthHandler()
         self.digest_auth_handler.set_users({self.USER: self.PASSWD})
         self.digest_auth_handler.set_realm(self.REALM)
diff --git a/Misc/ACKS b/Misc/ACKS
index 9c805b0..6d245cd 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1361,6 +1361,7 @@
 Thenault Sylvain
 Péter Szabó
 John Szakmeister
+Piotr Szczepaniak
 Amir Szekely
 Arfrever Frehtes Taifersar Arahesis
 Hideaki Takahashi