Issue #28435: Avoid no_proxy environment variable interfering with tests

Patch by Piotr Szczepaniak.

Lib/test/test_urllib2_localnet.py

@@ -323,6 +323,14 @@ class ProxyAuthTests(unittest.TestCase):
 
     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)
@@ -445,6 +453,7 @@ class TestUrlopen(unittest.TestCase):
             os.environ.update(old_environ)
         self.addCleanup(restore_environ, os.environ.copy())
         os.environ['NO_PROXY'] = '*'
+        os.environ['no_proxy'] = '*'
 
     def urlopen(self, url, data=None, **kwargs):
         l = []

Misc/ACKS

@@ -1450,6 +1450,7 @@ Al Sweigart
 Thenault Sylvain
 Péter Szabó
 John Szakmeister
+Piotr Szczepaniak
 Amir Szekely
 Maciej Szulik
 Arfrever Frehtes Taifersar Arahesis