[INFO] fetching crate piece 0.2.1...
[INFO] testing piece-0.2.1 against beta-2026-04-21 for beta-1.96-2
[INFO] extracting crate piece 0.2.1 into /workspace/builds/worker-2-tc2/source
[INFO] started tweaking crates.io crate piece 0.2.1
[INFO] finished tweaking crates.io crate piece 0.2.1
[INFO] tweaked toml for crates.io crate piece 0.2.1 written to /workspace/builds/worker-2-tc2/source/Cargo.toml
[INFO] validating manifest of crates.io crate piece 0.2.1 on toolchain beta-2026-04-21
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2026-04-21" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2026-04-21" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 1 package to latest compatible version
[INFO] [stderr]       Adding allocator-api2 v0.2.21 (available: v0.4.0)
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+beta-2026-04-21" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2026-04-21" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 8e65d2e4227b9c9ef79733f46cb9863014a66be9222a4d36170f4f7c2811f13b
[INFO] running `Command { std: "docker" "start" "-a" "8e65d2e4227b9c9ef79733f46cb9863014a66be9222a4d36170f4f7c2811f13b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "8e65d2e4227b9c9ef79733f46cb9863014a66be9222a4d36170f4f7c2811f13b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8e65d2e4227b9c9ef79733f46cb9863014a66be9222a4d36170f4f7c2811f13b", kill_on_drop: false }`
[INFO] [stdout] 8e65d2e4227b9c9ef79733f46cb9863014a66be9222a4d36170f4f7c2811f13b
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc2/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "RUSTDOCFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:d429b63d4308055ea97f60fb1d3dfca48854a00942f1bd2ad806beaf015945ec" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2026-04-21" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] f6e0d80518f5ff4814970ed60d0260f1371889dbe99717ce3d10107c60b571a2
[INFO] running `Command { std: "docker" "start" "-a" "f6e0d80518f5ff4814970ed60d0260f1371889dbe99717ce3d10107c60b571a2", kill_on_drop: false }`
[INFO] [stderr]    Compiling piece v0.2.1 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/lib.rs:2:38
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![cfg_attr(not(feature = "stable"), feature(allocator_api))]
[INFO] [stdout]   |                                      ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `piece` (lib) due to 1 previous error
[INFO] running `Command { std: "docker" "inspect" "f6e0d80518f5ff4814970ed60d0260f1371889dbe99717ce3d10107c60b571a2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f6e0d80518f5ff4814970ed60d0260f1371889dbe99717ce3d10107c60b571a2", kill_on_drop: false }`
[INFO] [stdout] f6e0d80518f5ff4814970ed60d0260f1371889dbe99717ce3d10107c60b571a2
