Description:
Envoy crashes with assertion failure if a redis cluster is removed.

• Management server sends redis cluster with CDS response
• Envoy is fully initialized
• Management server sends CDS update with out redis cluster
• Envoy tries to remove the cluster and crashes with the following assertion while removing membership update callback.

[2019-08-21 13:35:56.778][1462770][critical][assert] [bazel-out/darwin-fastbuild/bin/source/common/common/_virtual_includes/callback_impl_lib/common/common/callback_impl.h:70] assert failure: std::find_if(callbacks_.begin(), callbacks_.end(), [handle](const CallbackHolder& holder) -> bool { return handle == &holder; }) != callbacks_.end().

If I look at the callbacks_.size() here - it is actually zero.

https://github.com/envoyproxy/envoy/blob/master/source/common/common/callback_impl.h#L60

Any idea on callback is not present during removal?