[INFO] fetching crate rust-freqdist 0.1.5...
[INFO] testing rust-freqdist-0.1.5 against 1.55.0 for beta-1.56-1
[INFO] extracting crate rust-freqdist 0.1.5 into /workspace/builds/worker-0/source
[INFO] validating manifest of crates.io crate rust-freqdist 0.1.5 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 rust-freqdist 0.1.5
[INFO] finished tweaking crates.io crate rust-freqdist 0.1.5
[INFO] tweaked toml for crates.io crate rust-freqdist 0.1.5 written to /workspace/builds/worker-0/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[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-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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] 303393b11824e45d65184e98b2b0effd460ae552ec105b3bdce27c7a3dd3ccf9
[INFO] running `Command { std: "docker" "start" "-a" "303393b11824e45d65184e98b2b0effd460ae552ec105b3bdce27c7a3dd3ccf9", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "303393b11824e45d65184e98b2b0effd460ae552ec105b3bdce27c7a3dd3ccf9", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "303393b11824e45d65184e98b2b0effd460ae552ec105b3bdce27c7a3dd3ccf9", kill_on_drop: false }`
[INFO] [stdout] 303393b11824e45d65184e98b2b0effd460ae552ec105b3bdce27c7a3dd3ccf9
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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] 4c83830f600260c57b44478bfa660815274bbdd91c5ca99e42938afb68c170dd
[INFO] running `Command { std: "docker" "start" "-a" "4c83830f600260c57b44478bfa660815274bbdd91c5ca99e42938afb68c170dd", kill_on_drop: false }`
[INFO] [stderr]    Compiling rust-freqdist v0.1.5 (/opt/rustwide/workdir)
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.64s
[INFO] running `Command { std: "docker" "inspect" "4c83830f600260c57b44478bfa660815274bbdd91c5ca99e42938afb68c170dd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "4c83830f600260c57b44478bfa660815274bbdd91c5ca99e42938afb68c170dd", kill_on_drop: false }`
[INFO] [stdout] 4c83830f600260c57b44478bfa660815274bbdd91c5ca99e42938afb68c170dd
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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] [stdout] 8cbce6648318a1531baa4b8c528b45e34e2bcbaf65984277d4769b0aa169de5c
[INFO] running `Command { std: "docker" "start" "-a" "8cbce6648318a1531baa4b8c528b45e34e2bcbaf65984277d4769b0aa169de5c", kill_on_drop: false }`
[INFO] [stderr]    Compiling rust-freqdist v0.1.5 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> src/lib.rs:29:19
[INFO] [stdout]    |
[INFO] [stdout] 29 | #![cfg_attr(test, feature(test))]
[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 `rust-freqdist` due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "8cbce6648318a1531baa4b8c528b45e34e2bcbaf65984277d4769b0aa169de5c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8cbce6648318a1531baa4b8c528b45e34e2bcbaf65984277d4769b0aa169de5c", kill_on_drop: false }`
[INFO] [stdout] 8cbce6648318a1531baa4b8c528b45e34e2bcbaf65984277d4769b0aa169de5c