Issue12541 - Add UserWarning for unquoted realms

Lib/test/test_urllib2.py

@@ -1261,6 +1261,7 @@ class HandlerTests(unittest.TestCase):
             401, 'WWW-Authenticate: Basic realm=%s\r\n\r\n' % realm)
         opener.add_handler(auth_handler)
         opener.add_handler(http_handler)
+        with self.assertWarns(UserWarning):
             self._test_basic_auth(opener, auth_handler, "Authorization",
                                 realm, http_handler, password_manager,
                                 "http://acme.example.com/protected",

Lib/urllib/request.py

@@ -934,6 +934,9 @@ class AbstractBasicAuthHandler:
                 mo = AbstractBasicAuthHandler.rx.search(authreq)
                 if mo:
                     scheme, quote, realm = mo.groups()
+                    if quote not in ['"',"'"]:
+                        warnings.warn("Basic Auth Realm was unquoted",
+                                      UserWarning, 2)
                     if scheme.lower() == 'basic':
                         response = self.retry_http_basic_auth(host, req, realm)
                         if response and response.code != 401: