message: test BTree a bit more
diff: +use std::collections::{BTreeMap, BTreeSet};
  +
  #[derive(PartialEq, Eq, PartialOrd, Ord)]
  pub enum Foo {
  A(&'static str),
  @@ -6,11 +8,22 @@ pub enum Foo {
  }
  pub fn main() {
  - let mut b = std::collections::BTreeSet::new();
  + let mut b = BTreeSet::new();
  b.insert(Foo::A("\'"));
  b.insert(Foo::A("/="));
  b.insert(Foo::A("#"));
  b.insert(Foo::A("0o"));
  assert!(b.remove(&Foo::A("/=")));
  assert!(!b.remove(&Foo::A("/=")));
  +
  + // Also test a lower-alignment type, where the NodeHeader overlaps with
  + // the keys.
  + let mut b = BTreeSet::new();
  + b.insert(1024);
  + b.insert(7);
  +
  + let mut b = BTreeMap::new();
  + b.insert("bar", 1024);
  + b.insert("baz", 7);
  + for _val in b.iter_mut() {}
  }
  