pimd: send pim prune via correct interface when rpf upstream interface for a source changes

When the rpf upstream interface for a joined source changes, a prune was
being sent out the new rpf upstream interface that was intended for the old
upstream router.  The prune should be sent out the old rpf upstream
interface so that the old route for the multicast source is pruned.

Reviewed-by: Jafar Al-Gharaibeh <jafar@atcorp.com>
Signed-off-by: Taylor Bouvin <tbouvin@atcorp.com>
Tested-by: NetDEF CI System <cisystem@netdef.org>
3 files changed