message: Minor cleanup for metabuild hash
  At the time I wrote this I was unaware of the util function that did the same
  thing.
diff: -#![allow(deprecated)] // for SipHasher
  -
  use std::collections::{BTreeMap, HashMap};
  use std::fmt;
  -use std::hash::{Hash, Hasher, SipHasher};
  +use std::hash::{Hash, Hasher};
  use std::path::{Path, PathBuf};
  use std::rc::Rc;
  @@ -17,7 +15,7 @@ use core::{Dependency, PackageId, PackageIdSpec, SourceId, Summary};
  use core::{Edition, Feature, Features, WorkspaceConfig};
  use util::errors::*;
  use util::toml::TomlManifest;
  -use util::{Config, Filesystem};
  +use util::{Config, Filesystem, short_hash};
  pub enum EitherManifest {
  Real(Manifest),
  @@ -515,13 +513,11 @@ impl Manifest {
  }
  pub fn metabuild_path(&self, target_dir: Filesystem) -> PathBuf {
  - let mut hasher = SipHasher::new_with_keys(0, 0);
  - self.package_id().hash(&mut hasher);
  - let hash = hasher.finish();
  + let hash = short_hash(self.package_id());
  target_dir
  .into_path_unlocked()
  .join(".metabuild")
  - .join(format!("metabuild-{}-{:016x}.rs", self.name(), hash))
  + .join(format!("metabuild-{}-{}.rs", self.name(), hash))
  }
  }
  