message: minor: remove unused mut
diff: @@ -109,7 +109,7 @@ impl<'a> RegistryQueryer<'a> {
  self.registry_cache.insert(dep.clone(), Poll::Pending);
  return Poll::Pending;
  }
  - for summary in ret.iter_mut() {
  + for summary in ret.iter() {
  let mut potential_matches = self
  .replacements
  .iter()
  