add logging to case of downcasting false voter

src/governor/cc.rs

@@ -4,11 +4,11 @@ use ::raft::prelude::ConfChangeType::*;
 use std::collections::HashMap;
 use std::collections::{BTreeMap, BTreeSet};
 
-use crate::has_grades;
 use crate::instance::GradeVariant::*;
 use crate::instance::Instance;
 use crate::tier::Tier;
 use crate::traft::{Distance, RaftId};
+use crate::{has_grades, tlog};
 
 struct RaftConf<'a> {
     all: BTreeMap<RaftId, &'a Instance>,
@@ -126,7 +126,14 @@ pub(crate) fn raft_conf_change(
         let instance = match raft_conf.all.get(voter_id) {
             Some(instance) if eligible_for_vote(instance) => instance,
             // case when bootstrap leader from tier with `can_vote = false`
-            Some(_) => {
+            Some(Instance {
+                tier, instance_id, ..
+            }) => {
+                tlog!(
+                    Info,
+                    "instance with instance_id '{instance_id}' from \
+                     tier '{tier}' with 'can_vote' = false is in raft configuration as voter, making it follower"
+                );
                 let ccs = raft_conf.change_single(RemoveNode, *voter_id);
                 changes.push(ccs);
                 continue;