message: regain determinism
diff: @@ -11,7 +11,7 @@ enum ConflictStoreTrie {
  Leaf(BTreeMap<PackageId, ConflictReason>),
  /// a Node is a map from an element to a subTrie where
  /// all the Sets in the subTrie contains that element.
  - Node(HashMap<PackageId, ConflictStoreTrie>),
  + Node(BTreeMap<PackageId, ConflictStoreTrie>),
  }
  impl ConflictStoreTrie {
  @@ -59,7 +59,7 @@ impl ConflictStoreTrie {
  if let Some(pid) = iter.next() {
  if let ConflictStoreTrie::Node(p) = self {
  p.entry(pid)
  - .or_insert_with(|| ConflictStoreTrie::Node(HashMap::new()))
  + .or_insert_with(|| ConflictStoreTrie::Node(BTreeMap::new()))
  .insert(iter, con);
  } // else, We already have a subset of this in the ConflictStore
  } else {
  @@ -159,7 +159,7 @@ impl ConflictCache {
  pub fn insert(&mut self, dep: &Dependency, con: &BTreeMap<PackageId, ConflictReason>) {
  self.con_from_dep
  .entry(dep.clone())
  - .or_insert_with(|| ConflictStoreTrie::Node(HashMap::new()))
  + .or_insert_with(|| ConflictStoreTrie::Node(BTreeMap::new()))
  .insert(con.keys().cloned(), con.clone());
  trace!(
  