//! Emit the rename notice on every build.
//!
//! A crates.io description is read at most once, by one person, on the day they
//! add the dependency. `cargo:warning` prints on every build of this crate,
//! which is the only channel that reaches whoever pinned the old name years
//! ago. The failure mode in aprender#2546 was exactly that a stale pin resolved
//! *silently* — no error, no warning, a tool sixty versions behind.