[INFO] cloning repository https://github.com/thomwiggers/powerpolynomials
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/thomwiggers/powerpolynomials" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fthomwiggers%2Fpowerpolynomials", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fthomwiggers%2Fpowerpolynomials'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 66e737be9dea59a8c840af3fab729f5ea20cadf3
[INFO] testing thomwiggers/powerpolynomials against 1.55.0 for beta-1.56-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fthomwiggers%2Fpowerpolynomials" "/workspace/builds/worker-88/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-88/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/thomwiggers/powerpolynomials on toolchain 1.55.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/thomwiggers/powerpolynomials
[INFO] finished tweaking git repo https://github.com/thomwiggers/powerpolynomials
[INFO] tweaked toml for git repo https://github.com/thomwiggers/powerpolynomials written to /workspace/builds/worker-88/source/Cargo.toml
[INFO] crate git repo https://github.com/thomwiggers/powerpolynomials already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-88/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-88/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 3795112c0a2617a4c08055761271679f95d1d7eaf552b35bd1642ce65c591514
[INFO] running `Command { std: "docker" "start" "-a" "3795112c0a2617a4c08055761271679f95d1d7eaf552b35bd1642ce65c591514", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "3795112c0a2617a4c08055761271679f95d1d7eaf552b35bd1642ce65c591514", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "3795112c0a2617a4c08055761271679f95d1d7eaf552b35bd1642ce65c591514", kill_on_drop: false }`
[INFO] [stdout] 3795112c0a2617a4c08055761271679f95d1d7eaf552b35bd1642ce65c591514
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-88/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-88/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" "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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] f0bf1c5a7339f64a432e73c912150a3d67419437bd0b2d9d8c7f44d60563618e
[INFO] running `Command { std: "docker" "start" "-a" "f0bf1c5a7339f64a432e73c912150a3d67419437bd0b2d9d8c7f44d60563618e", kill_on_drop: false }`
[INFO] [stderr]    Compiling serde v1.0.36
[INFO] [stdout] error[E0432]: unresolved import `core::nonzero`
[INFO] [stdout]    --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/serde-1.0.36/src/lib.rs:215:19
[INFO] [stdout]     |
[INFO] [stdout] 215 |     pub use core::nonzero::{NonZero, Zeroable};
[INFO] [stdout]     |                   ^^^^^^^ could not find `nonzero` in `core`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/serde-1.0.36/src/lib.rs:89:35
[INFO] [stdout]    |
[INFO] [stdout] 89 | #![cfg_attr(feature = "unstable", feature(nonzero, specialization))]
[INFO] [stdout]    |                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] Some errors have detailed explanations: E0432, E0554.
[INFO] [stdout] 
[INFO] [stdout] For more information about an error, try `rustc --explain E0432`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `serde` due to 3 previous errors
[INFO] running `Command { std: "docker" "inspect" "f0bf1c5a7339f64a432e73c912150a3d67419437bd0b2d9d8c7f44d60563618e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f0bf1c5a7339f64a432e73c912150a3d67419437bd0b2d9d8c7f44d60563618e", kill_on_drop: false }`
[INFO] [stdout] f0bf1c5a7339f64a432e73c912150a3d67419437bd0b2d9d8c7f44d60563618e