[INFO] fetching crate driverkit 0.9.0...
[INFO] testing driverkit-0.9.0 against 1.55.0 for beta-1.56-1
[INFO] extracting crate driverkit 0.9.0 into /workspace/builds/worker-80/source
[INFO] validating manifest of crates.io crate driverkit 0.9.0 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 crates.io crate driverkit 0.9.0
[INFO] finished tweaking crates.io crate driverkit 0.9.0
[INFO] tweaked toml for crates.io crate driverkit 0.9.0 written to /workspace/builds/worker-80/source/Cargo.toml
[INFO] crate crates.io crate driverkit 0.9.0 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-80/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-80/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] 26aa00f5c7a52a7e411f0198adfae57261b081e1afc0e9f2d5189b0e621c6767
[INFO] running `Command { std: "docker" "start" "-a" "26aa00f5c7a52a7e411f0198adfae57261b081e1afc0e9f2d5189b0e621c6767", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "26aa00f5c7a52a7e411f0198adfae57261b081e1afc0e9f2d5189b0e621c6767", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "26aa00f5c7a52a7e411f0198adfae57261b081e1afc0e9f2d5189b0e621c6767", kill_on_drop: false }`
[INFO] [stdout] 26aa00f5c7a52a7e411f0198adfae57261b081e1afc0e9f2d5189b0e621c6767
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-80/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-80/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] 25d04748ae7c62a291f53770797f0b0b913b0d77837d2cae7d17024f4f54acea
[INFO] running `Command { std: "docker" "start" "-a" "25d04748ae7c62a291f53770797f0b0b913b0d77837d2cae7d17024f4f54acea", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling libc v0.2.93
[INFO] [stderr]    Compiling bitflags v1.2.1
[INFO] [stderr]    Compiling log v0.4.14
[INFO] [stderr]    Compiling x86 v0.41.0
[INFO] [stderr]    Compiling remove_dir_all v0.5.3
[INFO] [stderr]    Compiling cfg-if v1.0.0
[INFO] [stderr]    Compiling bit_field v0.10.1
[INFO] [stderr]    Compiling libc v0.1.12
[INFO] [stderr]    Compiling custom_error v1.9.2
[INFO] [stderr]    Compiling byteorder v1.4.3
[INFO] [stderr]    Compiling matches v0.1.8
[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/custom_error-1.9.2/src/lib.rs:3:35
[INFO] [stdout]   |
[INFO] [stdout] 3 | #![cfg_attr(feature = "unstable", feature(allocator_api, try_reserve))]
[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 `custom_error` due to 2 previous errors
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "25d04748ae7c62a291f53770797f0b0b913b0d77837d2cae7d17024f4f54acea", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "25d04748ae7c62a291f53770797f0b0b913b0d77837d2cae7d17024f4f54acea", kill_on_drop: false }`
[INFO] [stdout] 25d04748ae7c62a291f53770797f0b0b913b0d77837d2cae7d17024f4f54acea