RPF not updated when PIM neighbour goes down

[arundesigan]

Branch: stable/8.1

                                                                                                    11.1.1.1
                                                                        11.1.1.2    |---------[RP]

[Receiver] ---- [ Router] -------------[ Router]-------|
10.1.1.1. 10.1.1.2 |_______ [Sender]

In the above topology (simplified for explanation), the RPF (in the FHR) for the RP (20.1.1.1 & sender) gets resolved when the neighbourship between the routers (10.1.1.1 and 10.1.1.2) comes up. But when the neighbourship goes down, PIMd (in the FHR router) continues with the same RPF and keeps sending the Join pkts towards 10.1.1.2 & with 10.1.1.2 as the 'upstream-neighbour 'in the PIM Join packets. Is this expected? The RP is also not marked as unresolved / unknown. There is no dynamic routing involved here and routes are statically added, hence the route itself is not withdrawn.