message: Unify handling of `Entry` from `btree_map` and `hash_map`
diff: @@ -44,7 +44,7 @@ mod tests;
  #[cfg(test)]
  use std::collections::BTreeSet;
  use std::{
  - collections::{btree_map::Entry, hash_map, BTreeMap, HashMap, HashSet},
  + collections::{btree_map, hash_map, BTreeMap, HashMap, HashSet},
  convert::TryFrom,
  fmt::{self, Display, Formatter},
  fs, io, mem,
  @@ -1821,10 +1821,10 @@ fn insert_to_block_header_indices(
  if block_header.is_switch_block() {
  match switch_block_era_id_index.entry(block_header.era_id()) {
  - Entry::Vacant(entry) => {
  + btree_map::Entry::Vacant(entry) => {
  let _ = entry.insert(block_hash);
  }
  - Entry::Occupied(entry) => {
  + btree_map::Entry::Occupied(entry) => {
  if *entry.get() != block_hash {
  return Err(FatalStorageError::DuplicateEraIdIndex {
  era_id: block_header.era_id(),
  