Overwrite pystun server list.

* Non-responding servers in pystun's builtin list are causing node to
  crash upon starting up.

node/network_util.py

@@ -24,11 +24,9 @@
 )
 
 
-def init_additional_STUN_servers(servers=_ADDITIONAL_STUN_SERVERS):
-    """Inject list of additional STUN servers."""
-    server_set = set(stun.stun_servers_list)
-    server_set.update(servers)
-    stun.stun_servers_list = tuple(server_set)
+def set_stun_servers(servers=_ADDITIONAL_STUN_SERVERS):
+    """Manually set the list of good STUN servers."""
+    stun.stun_servers_list = tuple(servers)
 
 
 def get_NAT_status():

node/openbazaar.py

@@ -339,7 +339,7 @@ def ensure_database_setup(ob_ctx, defaults):
 
 def start(arguments):
     defaults = OpenBazaarContext.get_defaults()
-    network_util.init_additional_STUN_servers()
+    network_util.set_stun_servers()
 
     # Turn off checks that don't make sense in development mode
     if arguments.dev_mode:

test/test_network_util.py

@@ -1,4 +1,3 @@
-import collections
 import unittest
 
 import stun
@@ -8,25 +7,13 @@
 
 class TestNodeNetworkUtil(unittest.TestCase):
 
-    def test_init_additional_stun_servers(self):
-        stun_servers_pre = stun.stun_servers_list
+    def test_set_stun_servers(self):
         new_stun_servers = (
             'stun.openbazaar1.com',
             'stun.openbazaar2.com'
         )
-        network_util.init_additional_STUN_servers(servers=new_stun_servers)
-
-        counter = collections.Counter(stun.stun_servers_list)
-
-        # Check all new STUN servers are in.
-        for server in new_stun_servers:
-            self.assertEqual(counter[server], 1)
-
-        network_util.init_additional_STUN_servers(servers=new_stun_servers)
-
-        # Check no STUN server was removed or added twice.
-        for server in stun_servers_pre:
-            self.assertEqual(counter[server], 1)
+        network_util.set_stun_servers(servers=new_stun_servers)
+        self.assertItemsEqual(new_stun_servers, stun.stun_servers_list)
 
     def test_is_loopback_addr(self):
         self.assertTrue(network_util.is_loopback_addr("127.0.0.1"))