message: Add pointer equality to PartialEq for SourceId
diff: @@ -3,6 +3,7 @@ use std::collections::HashSet;
  use std::fmt::{self, Formatter};
  use std::hash::{self, Hash};
  use std::path::Path;
  +use std::ptr;
  use std::sync::Mutex;
  use std::sync::atomic::{AtomicBool, ATOMIC_BOOL_INIT};
  use std::sync::atomic::Ordering::SeqCst;
  @@ -438,6 +439,9 @@ impl fmt::Display for SourceId {
  // URL equality for other sources, ignoring the `precise` and `name` fields.
  impl PartialEq for SourceId {
  fn eq(&self, other: &SourceId) -> bool {
  + if ptr::eq(self.inner, other.inner) {
  + return true;
  + }
  if self.inner.kind != other.inner.kind {
  return false;
  }
  