[INFO] fetching crate mech-core 0.0.5...
[INFO] testing mech-core-0.0.5 against beta-2021-08-01 for beta-1.55-1
[INFO] extracting crate mech-core 0.0.5 into /workspace/builds/worker-29/source
[INFO] validating manifest of crates.io crate mech-core 0.0.5 on toolchain beta-2021-08-01
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-08-01" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate mech-core 0.0.5
[INFO] finished tweaking crates.io crate mech-core 0.0.5
[INFO] tweaked toml for crates.io crate mech-core 0.0.5 written to /workspace/builds/worker-29/source/Cargo.toml
[INFO] crate crates.io crate mech-core 0.0.5 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-08-01" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-29/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-29/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@sha256:34b6a614d2c27851fe6cbf88fbd1137609cefab8b10d0615aaeb6fd47975d74e" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2021-08-01" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 91758a96098abe52c2967172f7f51072b5f3e6dcdd5fe5c42f3cdc3e98943d35
[INFO] running `Command { std: "docker" "start" "-a" "91758a96098abe52c2967172f7f51072b5f3e6dcdd5fe5c42f3cdc3e98943d35", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "91758a96098abe52c2967172f7f51072b5f3e6dcdd5fe5c42f3cdc3e98943d35", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "91758a96098abe52c2967172f7f51072b5f3e6dcdd5fe5c42f3cdc3e98943d35", kill_on_drop: false }`
[INFO] [stdout] 91758a96098abe52c2967172f7f51072b5f3e6dcdd5fe5c42f3cdc3e98943d35
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-29/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-29/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@sha256:34b6a614d2c27851fe6cbf88fbd1137609cefab8b10d0615aaeb6fd47975d74e" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2021-08-01" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 647b75d6a11fd5adad6c9bec3cd6cc96d3d42a1dd7db49c07a4d6419ed42857e
[INFO] running `Command { std: "docker" "start" "-a" "647b75d6a11fd5adad6c9bec3cd6cc96d3d42a1dd7db49c07a4d6419ed42857e", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling proc-macro2 v1.0.12
[INFO] [stderr]    Compiling autocfg v1.0.0
[INFO] [stderr]    Compiling syn v1.0.18
[INFO] [stderr]    Compiling serde v1.0.106
[INFO] [stderr]    Compiling ahash v0.3.4
[INFO] [stderr]    Compiling hashbrown v0.7.2
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]   --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/hashbrown-0.7.2/src/lib.rs:15:5
[INFO] [stdout]    |
[INFO] [stdout] 15 | /     feature(
[INFO] [stdout] 16 | |         alloc_layout_extra,
[INFO] [stdout] 17 | |         allocator_api,
[INFO] [stdout] 18 | |         ptr_offset_from,
[INFO] [stdout] ...  |
[INFO] [stdout] 22 | |         specialization,
[INFO] [stdout] 23 | |     )
[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 `hashbrown` 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" "647b75d6a11fd5adad6c9bec3cd6cc96d3d42a1dd7db49c07a4d6419ed42857e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "647b75d6a11fd5adad6c9bec3cd6cc96d3d42a1dd7db49c07a4d6419ed42857e", kill_on_drop: false }`
[INFO] [stdout] 647b75d6a11fd5adad6c9bec3cd6cc96d3d42a1dd7db49c07a4d6419ed42857e
