Reference:
https://src.fedoraproject.org/rpms/python-requests/blob/rawhide/f/requests-2.12.4-tests_nonet.patch
--- requests-2.12.4/tests/testserver/server.py	2016-12-21 11:31:56.000000000 -0800
+++ requests-2.12.4/tests/testserver/server.py.new	2016-12-30 10:40:06.085995065 -0800
@@ -27,7 +27,7 @@
     """Dummy server using for unit testing"""
     WAIT_EVENT_TIMEOUT = 5
 
-    def __init__(self, handler=None, host='localhost', port=0, requests_to_handle=1, wait_to_close_event=None):
+    def __init__(self, handler=None, host='127.0.0.1', port=0, requests_to_handle=1, wait_to_close_event=None):
         super(Server, self).__init__()
 
         self.handler = handler or consume_socket_content
