bug#52072: [core-updates-frozen] rust-bitflags 1.2.1 fails to build.

[Brendan Tildesley]

starting phase `configure'
bitflags-1.2.1/.gitignore
bitflags-1.2.1/build.rs
bitflags-1.2.1/Cargo.toml.orig
bitflags-1.2.1/Cargo.toml
bitflags-1.2.1/CHANGELOG.md
bitflags-1.2.1/CODE_OF_CONDUCT.md
bitflags-1.2.1/LICENSE-APACHE
bitflags-1.2.1/LICENSE-MIT
bitflags-1.2.1/README.md
bitflags-1.2.1/src/example_generated.rs
bitflags-1.2.1/src/lib.rs
bitflags-1.2.1/.cargo_vcs_info.json
phase `configure' succeeded after 0.0 seconds
starting phase `patch-generated-file-shebangs'
phase `patch-generated-file-shebangs' succeeded after 0.0 seconds
starting phase `patch-cargo-checksums'
patch-cargo-checksums: generate-checksums for 
guix-vendor/rust-bitflags-1.2.1.crate
phase `patch-cargo-checksums' succeeded after 0.0 seconds
starting phase `build'
error: could not find `Cargo.toml` in 
`/tmp/guix-build-rust-bitflags-1.2.1.drv-0` or any parent directory
error: in phase 'build': uncaught exception:
%exception #<&invoke-error program: "cargo" arguments: ("build" "--release") 
exit-status: 101 term-signal: #f stop-signal: #f> 
phase `build' failed after 0.0 seconds
command "cargo" "build" "--release" failed with status 101