auditable-build panics on Beta

[Monadic-Cat]

I have a crate, mbot for which auditable-build successfully runs and this all works for on Stable, but for which auditable-build panics when building on Beta.
Some relevant command output:

jmn@neogreen:~/Projects/mprojects/mbot$ RUST_BACKTRACE=1 cargo +beta run --release --features auditable-data
   Compiling mbot v0.1.0 (/home/jmn/Projects/mprojects/mbot)
error: failed to run custom build command for `mbot v0.1.0 (/home/jmn/Projects/mprojects/mbot)`

Caused by:
  process didn't exit successfully: `/home/jmn/Projects/mprojects/mbot/target/release/build/mbot-35641d5a1f06aff7/build-script-build` (exit code: 101)
  --- stdout
  cargo:rerun-if-changed=data/maddie.json

  --- stderr
  thread 'main' panicked at 'no entry found for key', cargo/registry/src/github.com-1ecc6299db9ec823/auditable-serde-0.1.0/src/lib.rs:307:51
  stack backtrace:
     0: rust_begin_unwind
               at /rustc/9f0e6fa94be6f97c736e51811d7b58904edfa8cb/library/std/src/panicking.rs:475
     1: core::panicking::panic_fmt
               at /rustc/9f0e6fa94be6f97c736e51811d7b58904edfa8cb/library/core/src/panicking.rs:85
     2: core::option::expect_failed
               at /rustc/9f0e6fa94be6f97c736e51811d7b58904edfa8cb/library/core/src/option.rs:1213
     3: core::option::Option<T>::expect
     4: <std::collections::hash::map::HashMap<K,V,S> as core::ops::index::Index<&Q>>::index
     5: <auditable_serde::VersionInfo as core::convert::TryFrom<&cargo_metadata::Metadata>>::try_from
     6: auditable_build::collect_dependency_list
     7: build_script_build::main
     8: core::ops::function::FnOnce::call_once
  note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[Monadic-Cat]

Upon regenerating the Cargo.lock in mbot, this issue vanishes. Somehow or other, my Cargo.lock was malformed. Nemo157 on Discord has guessed that this is related to rust-lang/cargo#8522.

[Shnatsel]

This is caused by an upstream bug: rust-lang/cargo#8756

I'll keep this open until the upstream issue is resolved.

[Shnatsel]

The upstream bug is fixed, so closing this issue.