[INFO] cloning repository https://github.com/ShallowFeather/a-Hello-world-os
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/ShallowFeather/a-Hello-world-os" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FShallowFeather%2Fa-Hello-world-os", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FShallowFeather%2Fa-Hello-world-os'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] a32fd2ae09966585193f6f7b437a9faffb7174b3
[INFO] testing ShallowFeather/a-Hello-world-os against 1.55.0 for beta-1.56-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FShallowFeather%2Fa-Hello-world-os" "/workspace/builds/worker-116/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-116/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/ShallowFeather/a-Hello-world-os 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/ShallowFeather/a-Hello-world-os
[INFO] finished tweaking git repo https://github.com/ShallowFeather/a-Hello-world-os
[INFO] tweaked toml for git repo https://github.com/ShallowFeather/a-Hello-world-os written to /workspace/builds/worker-116/source/Cargo.toml
[INFO] crate git repo https://github.com/ShallowFeather/a-Hello-world-os 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] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded bootloader v0.10.4
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-116/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-116/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] 76bfa2b251e9fd437de84de967812a97f0ab24d4629cc2aa14af318622d953bb
[INFO] running `Command { std: "docker" "start" "-a" "76bfa2b251e9fd437de84de967812a97f0ab24d4629cc2aa14af318622d953bb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "76bfa2b251e9fd437de84de967812a97f0ab24d4629cc2aa14af318622d953bb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "76bfa2b251e9fd437de84de967812a97f0ab24d4629cc2aa14af318622d953bb", kill_on_drop: false }`
[INFO] [stdout] 76bfa2b251e9fd437de84de967812a97f0ab24d4629cc2aa14af318622d953bb
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-116/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-116/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] 06d9cea7a89bacb38ad9e53665c4035a7b6b4bccbad0b91b2caa492d77d3ee2e
[INFO] running `Command { std: "docker" "start" "-a" "06d9cea7a89bacb38ad9e53665c4035a7b6b4bccbad0b91b2caa492d77d3ee2e", kill_on_drop: false }`
[INFO] [stderr]    Compiling bootloader v0.10.4
[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/bootloader-0.10.4/src/lib.rs:67:1
[INFO] [stdout]    |
[INFO] [stdout] 67 | #![feature(asm)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^
[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/bootloader-0.10.4/src/lib.rs:68:1
[INFO] [stdout]    |
[INFO] [stdout] 68 | #![feature(maybe_uninit_extra)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[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/bootloader-0.10.4/src/lib.rs:69:1
[INFO] [stdout]    |
[INFO] [stdout] 69 | #![feature(maybe_uninit_slice)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 3 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `bootloader` due to 4 previous errors
[INFO] running `Command { std: "docker" "inspect" "06d9cea7a89bacb38ad9e53665c4035a7b6b4bccbad0b91b2caa492d77d3ee2e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "06d9cea7a89bacb38ad9e53665c4035a7b6b4bccbad0b91b2caa492d77d3ee2e", kill_on_drop: false }`
[INFO] [stdout] 06d9cea7a89bacb38ad9e53665c4035a7b6b4bccbad0b91b2caa492d77d3ee2e