Fix nits in brctl removal (vif_plug_linux_bridge)

This commit fixes the nits caught in:
Id03be72e22302a0954f3e47c116f389cb4304c03

Change-Id: Ib7fcb3c6f809222c33d163fe7a2d854016c7d392
Signed-off-by: Jan Gutter <jan.gutter@netronome.com>

releasenotes/notes/brctl-removal-a5b0e69b865afa57.yaml

@@ -2,7 +2,7 @@
 other:
   - |
     With this release, packagers of ``os-vif`` no longer need to create a
-    depency on ``brctl``. ``brctl`` is largely considered obsolete and has
+    dependency on ``brctl``. ``brctl`` is largely considered obsolete and has
     been replaced with iproute2 by default in many linux distributions.
     RHEL 8 will not ship ``brctl`` in its default repos. As part of a larger
     effort to remove usage of ``brctl`` from OpenStack ``os-vif`` has

vif_plug_linux_bridge/linux_net.py

@@ -102,8 +102,11 @@ def _disable_ipv6(bridge):
        privsep context.
     :param bridge: string bridge name
     """
-    disv6 = ('/proc/sys/net/ipv6/conf/%s/disable_ipv6' %
-             bridge)
+    # NOTE(sean-k-mooney): os-vif disables ipv6 to ensure the Bridge
+    # does not aquire an ipv6 auto config or link local adress.
+    # This is required to prevent bug 1302080.
+    # https://bugs.launchpad.net/neutron/+bug/1302080
+    disv6 = ('/proc/sys/net/ipv6/conf/%s/disable_ipv6' % bridge)
     if os.path.exists(disv6):
         with open(disv6, 'w') as f:
             f.write('1')
@@ -123,15 +126,16 @@ def _update_bridge_routes(interface, bridge):
     # NOTE(danms): We also need to copy routes to the bridge so as
     #              not to break existing connectivity on the interface
     old_routes = []
-    out, err = processutils.execute('ip', 'route', 'show', 'dev',
-                                    interface)
+    out, _ = processutils.execute('ip', 'route', 'show', 'dev',
+                                  interface)
     for line in out.split('\n'):
         fields = line.split()
         if fields and 'via' in fields:
             old_routes.append(fields)
             processutils.execute('ip', 'route', 'del', *fields)
-            out, err = processutils.execute('ip', 'addr', 'show', 'dev',
-                                            interface, 'scope', 'global')
+
+    out, _ = processutils.execute('ip', 'addr', 'show', 'dev',
+                                  interface, 'scope', 'global')
     for line in out.split('\n'):
         fields = line.split()
         if fields and fields[0] == 'inet':

vif_plug_linux_bridge/tests/unit/test_linux_net.py

@@ -120,8 +120,7 @@ class LinuxNetTest(testtools.TestCase):
            followed by the bridge. This is required to work around
            https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1399064
         """
-        mock_dev_exists.return_value = next(lambda: (yield False),
-                                            (yield True))
+        mock_dev_exists.side_effect = [False, True]
         linux_net._ensure_bridge_privileged("fake-bridge", "fake-interface",
                                             None, False, mtu=1500)
         calls = [mock.call('fake-interface', 1500),