meilisearch: Cannot build MeiliSearch v0.19.0 as NixOS package

Describe the bug I tried to use MeiliSearch on my NixOS server today, but noticed the official repos only have v0.9, so I tried to update it. I took the build script from the official repository and upped the version and fixed the hash of the source code. The build process stops with an error as seen below.

To Reproduce Steps to reproduce the behavior:

1. Run NixOS 20.09
2. Download this Nix expression: https://gist.github.com/michcioperz/4ecdeaf7921d63784eedf7197eafcb71
3. Run nix-build meilisearch.nix (the filename you saved to)
4. An error like this should show up during the vendoring phase:

error: failed to sync

Caused by:
  found duplicate version of package `pest v2.1.3` vendored from two sources:

        source 1: https://github.com/pest-parser/pest.git?rev=51fd1d49f1041f7839975664ef71fe15c7dcaf67#51fd1d49
        source 2: registry `https://github.com/rust-lang/crates.io-index`
Traceback (most recent call last):
  File "/nix/store/m6x1vskdlgsray23j2m2k5j7xzgcjhry-cargo-vendor-normalise/bin/.cargo-vendor-normalise-wrapped", line 42, in <module>
    main()
  File "/nix/store/m6x1vskdlgsray23j2m2k5j7xzgcjhry-cargo-vendor-normalise/bin/.cargo-vendor-normalise-wrapped", line 17, in main
    assert list(data.keys()) == ["source"]
AssertionError
builder for '/nix/store/vm7f4lngx8ar6qbh0n1snrwrscldwab8-meilisearch-0.19.0-vendor.tar.gz.drv' failed with exit code 1
cannot build derivation '/nix/store/cjxkk5frkqdikx6rzvyjlbviz2mlqd99-meilisearch-0.19.0.drv': 1 dependencies couldn't be built
error: build of '/nix/store/cjxkk5frkqdikx6rzvyjlbviz2mlqd99-meilisearch-0.19.0.drv' failed

Expected behavior The vendoring process should finish and Nix should complain that the hash of the vendor directory is different from what I told it to expect.

Desktop:

• OS: NixOS 20.09

Additional context NixOS is really into reproducible builds and pinning hashes of all things that are downloaded, so the first part of the process of building a package of something in Rust is vendoring the dependencies and checking that the hash of vendor directory matches what was given in the build script. Vendoring doesn’t complete successfully, because there are two colliding definitions of pest 2.1.3 package: a crates.io version depended on by pest_derive and a few other pest_* crates, and a git version depended on by meilisearch directly. If I understand correctly the problem would go away if pest had a new release on crates.io so you wouldn’t have to use a git version, but its maintainer is busy as seen in https://github.com/pest-parser/pest/issues/491 and https://github.com/pest-parser/pest/pull/454