BTreeMap: gather and decompose reusable tree fixing functions This is kind of pushing it as a standalone refactor, probably only useful for #81075 (or similar). r? `@Mark-Simulacrum`
BTreeMap: gather and decompose reusable tree fixing functions This is kind of pushing it as a standalone refactor, probably only useful for #81075 (or similar). r? `@Mark-Simulacrum`