createRustPackage fails for packages which use the patch feature in Cargo.toml

[jamii]

Describe the bug

When there is a [patch] section in Cargo.toml, calling cargo build --frozen will attempt to redownload the patch and then fail because of the --frozen.

This is arguably a cargo bug, because it appears that the patch is already vendored correctly.

To Reproduce

Minimal repro at https://github.com/jamii/rust-nix-patch.

jamie@machine:~/rust-nix-patch$ nix-build default.nix 
these derivations will be built:
  /nix/store/ghx01p7n275i8kalqvcbz3mqpqwiz911-rust-nix-patch.drv
building '/nix/store/ghx01p7n275i8kalqvcbz3mqpqwiz911-rust-nix-patch.drv'...
unpacking sources
unpacking source archive /nix/store/ya7anvmgxgj38c6lhshi5nf79xqm0l9n-source
source root is source
unpacking source archive /nix/store/99w9c3z1nwgw85d6drn38926h89k19m9-rust-nix-patch-vendor
patching sources
configuring
building
++ env CC_x86_64-unknown-linux-gnu=/nix/store/qy6rb8p4fg1p3xfw0g6wz6iirxbdxizp-gcc-wrapper-8.3.0/bin/cc CXX_x86_64-unknown-linux-gnu=/nix/store/qy6rb8p4fg1p3xfw0g6wz6iirxbdxizp-gcc-wrapper-8.3.0/bin/c++ CC_x86_64-unknown-linux-gnu=/nix/store/qy6rb8p4fg1p3xfw0g6wz6iirxbdxizp-gcc-wrapper-8.3.0/bin/cc CXX_x86_64-unknown-linux-gnu=/nix/store/qy6rb8p4fg1p3xfw0g6wz6iirxbdxizp-gcc-wrapper-8.3.0/bin/c++ cargo build --release --target x86_64-unknown-linux-gnu --frozen
    Updating git repository `https://github.com/jamii/regex.git`
error: failed to resolve patches for `https://github.com/rust-lang/crates.io-index`

Caused by:
  failed to load source for a dependency on `regex`

Caused by:
  Unable to update https://github.com/jamii/regex.git

Caused by:
  failed to clone into: /build/git/db/regex-fac71ca280a2847b

Caused by:
  attempting to update a git repository, but --frozen was specified
builder for '/nix/store/ghx01p7n275i8kalqvcbz3mqpqwiz911-rust-nix-patch.drv' failed with exit code 101
error: build of '/nix/store/ghx01p7n275i8kalqvcbz3mqpqwiz911-rust-nix-patch.drv' failed

Metadata

jamie@machine:~$ nix run nixpkgs.nix-info -c nix-info -m
 - system: `"x86_64-linux"`
 - host os: `Linux 4.19.80, NixOS, 20.03pre197685.f35f0880f2c (Markhor)`
 - multi-user?: `yes`
 - sandbox: `yes`
 - version: `nix-env (Nix) 2.3.1`
 - channels(jamie): `""`
 - channels(root): `"nixos-20.03pre197685.f35f0880f2c"`
 - nixpkgs: `/nix/var/nix/profiles/per-user/root/channels/nixos`

[jamii]

rust-lang/cargo#5805 (comment) suggests that this is intentional behavior in cargo

[aaronjanse]

This is still important to me

[jamii]

The minimal repro above still does not work.

[andrewbaxter]

Bump.

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/fixing-the-polars-package-cargo-patch-frozen/22901/1

[nixos-discourse]

This issue has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/rust-packaging-issue-unable-to-fetch-git-dependencies-correctly/46547/1