From 173e7e425083f51e122ecb7d602bb565b49e1b8f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
 <marmarek@invisiblethingslab.com>
Date: Mon, 26 Feb 2018 02:52:27 +0100
Subject: [PATCH] vm: fix calling vm.detach_network() when really needed

*oldvalue* argument to property event handler is provided only when the
value was not default. Check vm.netvm directly to resolve also default.
---
 qubes/vm/mix/net.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/qubes/vm/mix/net.py b/qubes/vm/mix/net.py
index 85d06dd2..0562d131 100644
--- a/qubes/vm/mix/net.py
+++ b/qubes/vm/mix/net.py
@@ -412,7 +412,8 @@ class NetVMMixin(qubes.events.Emitter):
                     'Cannot dynamically attach to stopped NetVM: {!r}'.format(
                         newvalue))
 
-        if oldvalue is not None:
+        # don't check oldvalue, because it's missing if it was default
+        if self.netvm is not None:
             if self.is_running():
                 self.detach_network()