We need to notify when the channel dispatcher calls HandleChannels on
us with a channel we already handle. However, we don't want to notify
if we claim a new incoming channel which doesn't actually have
anything interesting in it yet.
For example, a new channel pops up just to give a delivery
notification. We want (or, need) to handle it but don't want to notify
for it.
Fixes: https://bugzilla.gnome.org/show_bug.cgi?id=666243
Signed-off-by: Jonny Lamb <jonnylamb@gnome.org>
69e26c6dee