Since 03a5a85d, NMDeviceTeam was trying to use priv->teamd_pid to
decide whether a teamd_dbus_vanished() call indicated "teamd hasn't
been started yet" or "teamd was previously started and has now
exited". But this resulted in a race condition, where at startup, a
device could call g_dbus_watch_name(), then launch teamd (causing
teamd_pid to get set), and then have gdbus report that teamd hasn't
been started yet before the newly-launched teamd managed to grab the
bus name. Since teamd_pid would already be set when
teamd_dbus_vanished() was called, it would decide that this meant
"teamd was previously started and has now exited", so it would call
teamd_cleanup(), killing the just-started teamd process.
Fix this by having teamd_dbus_vanished() check priv->tdc instead,
which doesn't get set until after the first teamd_dbus_appeared()
call.
f0e74622cc