[INFO] fetching crate niobium 0.0.0...
[INFO] testing niobium-0.0.0 against 1.55.0 for beta-1.56-1
[INFO] extracting crate niobium 0.0.0 into /workspace/builds/worker-1/source
[INFO] validating manifest of crates.io crate niobium 0.0.0 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 niobium 0.0.0
[INFO] finished tweaking crates.io crate niobium 0.0.0
[INFO] tweaked toml for crates.io crate niobium 0.0.0 written to /workspace/builds/worker-1/source/Cargo.toml
[INFO] crate crates.io crate niobium 0.0.0 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] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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] 244aa3568ff7228587162f509179f1c9e6fa4bc99af3511594eaf7ef0ba59dd0
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "244aa3568ff7228587162f509179f1c9e6fa4bc99af3511594eaf7ef0ba59dd0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "244aa3568ff7228587162f509179f1c9e6fa4bc99af3511594eaf7ef0ba59dd0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "244aa3568ff7228587162f509179f1c9e6fa4bc99af3511594eaf7ef0ba59dd0", kill_on_drop: false }`
[INFO] [stdout] 244aa3568ff7228587162f509179f1c9e6fa4bc99af3511594eaf7ef0ba59dd0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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] e997600976189bd0ac947e84fbfab74ec8af2f9160d4cc9a4c9c1a1fe6d77fc7
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "e997600976189bd0ac947e84fbfab74ec8af2f9160d4cc9a4c9c1a1fe6d77fc7", kill_on_drop: false }`
[INFO] [stderr]    Compiling niobium v0.0.0 (/opt/rustwide/workdir)
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.74s
[INFO] running `Command { std: "docker" "inspect" "e997600976189bd0ac947e84fbfab74ec8af2f9160d4cc9a4c9c1a1fe6d77fc7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e997600976189bd0ac947e84fbfab74ec8af2f9160d4cc9a4c9c1a1fe6d77fc7", kill_on_drop: false }`
[INFO] [stdout] e997600976189bd0ac947e84fbfab74ec8af2f9160d4cc9a4c9c1a1fe6d77fc7
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 6fa063bef162db8ac095da604908178f9f2b094aab2dcd9e22cda443fca8d71b
[INFO] running `Command { std: "docker" "start" "-a" "6fa063bef162db8ac095da604908178f9f2b094aab2dcd9e22cda443fca8d71b", kill_on_drop: false }`
[INFO] [stderr]    Compiling niobium v0.0.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> examples/hello_magic.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(start)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: language item required, but not found: `eh_personality`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 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 `niobium` due to 3 previous errors
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "6fa063bef162db8ac095da604908178f9f2b094aab2dcd9e22cda443fca8d71b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6fa063bef162db8ac095da604908178f9f2b094aab2dcd9e22cda443fca8d71b", kill_on_drop: false }`
[INFO] [stdout] 6fa063bef162db8ac095da604908178f9f2b094aab2dcd9e22cda443fca8d71b