[INFO] fetching crate writedown 0.1.0...
[INFO] testing writedown-0.1.0 against 1.59.0 for beta-1.60-1
[INFO] extracting crate writedown 0.1.0 into /workspace/builds/worker-18/source
[INFO] validating manifest of crates.io crate writedown 0.1.0 on toolchain 1.59.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.59.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate writedown 0.1.0
[INFO] finished tweaking crates.io crate writedown 0.1.0
[INFO] tweaked toml for crates.io crate writedown 0.1.0 written to /workspace/builds/worker-18/source/Cargo.toml
[INFO] crate crates.io crate writedown 0.1.0 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.59.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-18/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-18/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@sha256:0cd99ca24d8e8c98e67c542213511d985b8778b5bdcbb160e038429496686047" "/opt/rustwide/cargo-home/bin/cargo" "+1.59.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 025f22cbadbf2c14caef3923efe12f98934da7ef29f8d91d33abd6204c6b3963
[INFO] running `Command { std: "docker" "start" "-a" "025f22cbadbf2c14caef3923efe12f98934da7ef29f8d91d33abd6204c6b3963", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "025f22cbadbf2c14caef3923efe12f98934da7ef29f8d91d33abd6204c6b3963", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "025f22cbadbf2c14caef3923efe12f98934da7ef29f8d91d33abd6204c6b3963", kill_on_drop: false }`
[INFO] [stdout] 025f22cbadbf2c14caef3923efe12f98934da7ef29f8d91d33abd6204c6b3963
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-18/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-18/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@sha256:0cd99ca24d8e8c98e67c542213511d985b8778b5bdcbb160e038429496686047" "/opt/rustwide/cargo-home/bin/cargo" "+1.59.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 54a0cff997fab1b6e984162e61b87ceea3fed6b78193efbec01046e9cead251b
[INFO] running `Command { std: "docker" "start" "-a" "54a0cff997fab1b6e984162e61b87ceea3fed6b78193efbec01046e9cead251b", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling writedown v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:2:12
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(assert_matches)]
[INFO] [stdout]   |            ^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `writedown` due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "54a0cff997fab1b6e984162e61b87ceea3fed6b78193efbec01046e9cead251b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "54a0cff997fab1b6e984162e61b87ceea3fed6b78193efbec01046e9cead251b", kill_on_drop: false }`
[INFO] [stdout] 54a0cff997fab1b6e984162e61b87ceea3fed6b78193efbec01046e9cead251b