[Pkg-rust-maintainers] Bug#1137611: Test "builds_local_registry" tries to open Cargo.lock in write mode

[kpcyrd]

Package: librust-tame-index-dev
Version: 0.26.2-1
Severity: serious

When investigating the sha2-0.10 transition being stuck, I noticed the test 
seems unrelated to sha2, but is instead related to filesystem permissions. I'm 
not sure why this was only flagged on riscv64, and how the test has passed in 
the past.

I also noticed there have been new uploads to tame-index in the meantime, so 
this problem may have been solved already, but the patches I looked into seemed 
unrelated to this specific test.

https://web.archive.org/web/20260525194927/https://ci.debian.net/data/autopkgtest/testing/riscv64/r/rust-tame-index/71210417/log.gz

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816s thread 'builds_local_registry' (14929) panicked at tests/local.rs:22:25:
816s failed to gather metadata: CargoMetadata { stderr: "error: failed to write 
/usr/share/cargo/registry/tame-index-0.26.2/Cargo.lock\n\nCaused by:\n  failed 
to open: /usr/share/cargo/registry/tame-index-0.26.2/Cargo.lock\n\nCaused by:\n 
Permission denied (os error 13)\n" }
816s stack backtrace:
816s    0: __rustc::rust_begin_unwind
816s              at /usr/src/rustc-1.94.1/library/std/src/panicking.rs:689:5
816s    1: core::panicking::panic_fmt
816s              at /usr/src/rustc-1.94.1/library/core/src/panicking.rs:80:14
816s    2: core::result::unwrap_failed
816s              at /usr/src/rustc-1.94.1/library/core/src/result.rs:1867:5
816s    3: core::result::Result<T,E>::expect
816s              at /usr/src/rustc-1.94.1/library/core/src/result.rs:1185:23
816s    4: local::builds_local_registry
816s              at ./tests/local.rs:22:25
816s    5: local::builds_local_registry::{{closure}}
816s              at ./tests/local.rs:10:27
816s    6: core::ops::function::FnOnce::call_once
816s              at /usr/src/rustc-1.94.1/library/core/src/ops/function.rs:250:5
816s    7: core::ops::function::FnOnce::call_once
816s              at /usr/src/rustc-1.94.1/library/core/src/ops/function.rs:250:5
816s note: Some details are omitted, run with `RUST_BACKTRACE=full` for a 
verbose backtrace.
816s
816s
816s failures:
816s     builds_local_registry
816s
816s test result: FAILED. 2 passed; 1 failed; 0 ignored; 0 measured; 0 filtered 
out; finished in 1.27s
816s
816s error: test failed, to rerun pass `--test local`

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