Fix ipv6 test and pytest collection

On some systems that test would fail because netifaces.AF_INET6 wound
have a different value than 10 (30 in my case).

Mocking it fixes the tests.

Also includes a fix that prevented running tests from pytest because
collection would fail due to .eggs folder.

Change-Id: Ic0be3ec3057adb969472fbbb5d8e257c4209d185

setup.cfg

@@ -167,7 +167,7 @@ mistral.actions =
     tripleo.role.list = tripleo_common.actions.plan:ListRolesAction
 
 [tool:pytest]
-norecursedirs = .git .tox dist
+norecursedirs = .eggs .git .tox dist
 log_cli = true
 
 [flake8]

tripleo_common/tests/image/test_image_uploader.py

@@ -113,6 +113,7 @@ class TestImageUploadManager(base.TestCase):
 
     @mock.patch('netifaces.ifaddresses')
     @mock.patch('netifaces.interfaces')
+    @mock.patch('netifaces.AF_INET6', 10)
     def test_get_undercloud_registry_ipv6(self, mock_interfaces,
                                           mock_addresses):