Cargo sets CARGO_PKG_* for every crate it compiles and buck2 sets none, so crates that read them (serde_core and thiserror in build.rs, serde_derive and thiserror-impl through env!) fail one at a time as the graph grows. Provide them to every crate, as Cargo does. Must sit above [vendor]: TOML keys after a table header belong to that table.

6cargo_env = true