malachite-bigint is needed for the Malachite/RustPython dependency chain:

malachite-base -> malachite-nz -> malachite-bigint ->
malachite-bigint-0.2 -> rustpython-ast 0.4 -> rustpython-parser 0.4 ->
pyo3-stub-gen-derive 0.23.0.

This package intentionally packages 0.9.1 because malachite-bigint 0.9.2
requires malachite-base 0.9.2 and malachite-nz 0.9.2, while Debian unstable
currently has malachite-base 0.9.1 and malachite-nz 0.9.1. Version 0.9.1 is
the matching package needed to continue the current dependency chain.

Build validation on 2026-07-16:

* Built with ./build.sh malachite-bigint against unstable, using
  rust-malachite-base 0.9.1-1 and rust-malachite-nz 0.9.1-1 from sid.
* sbuild result: Status: successful; Lintian: successful (worst tag: warn).
* autopkgtest result: pass. Generated tests passed for @, default,
  num-bigint, std, and the bare librust-malachite-bigint-dev package.
* The debcargo-conf helper reported UNKNOWN while analyzing autopkgtest, but
  the raw autopkgtest log and sbuild summary show a successful run.
* Explicit deep lintian with --display-info --pedantic reports only expected
  review-stage tags: distribution-and-changes-mismatch for the generated
  UNRELEASED changelog distribution, extended-description-is-probably-too-short,
  package-contains-documentation-outside-usr-share-doc for README.md,
  package-uses-old-debhelper-compat-version 13, and
  upstream-metadata-file-is-missing.
