commit 1d89bc0004ec27fbc0c89f17861118c78d7eeab5 (HEAD, origin/master, origin/HEAD, master)
Author: Dan Winship <danw@gnome.org>
Date:   Fri Jan 4 11:53:03 2013 -0500

    systemd: set KillMode=process
    
    By default, when shutting NM down, systemd will kill everything in its
    cgroup. But this can cause problems (eg, NM thinking that dhclient
    crashed and then taking down an interface that it would otherwise have
    left up). Fix this by setting KillMode=process, which tells systemd to
    only kill NM itself, and let NM kill its children.
    
    https://bugzilla.redhat.com/show_bug.cgi?id=876218

Index: network-manager/data/NetworkManager.service.in
===================================================================
--- network-manager.orig/data/NetworkManager.service.in	2013-01-05 20:18:09.943472117 +0100
+++ network-manager/data/NetworkManager.service.in	2013-01-05 20:18:09.943472117 +0100
@@ -10,6 +10,8 @@
 # with LOG_PERROR when run in foreground. But systemd redirects stderr to
 # syslog by default, which results in logging each message twice.
 StandardError=null
+# NM doesn't want systemd to kill its children for it
+KillMode=process
 
 [Install]
 WantedBy=multi-user.target