[INFO] fetching crate tokio-lk 0.2.2...
[INFO] testing tokio-lk-0.2.2 against 1.49.0 for beta-1.50-1
[INFO] extracting crate tokio-lk 0.2.2 into /workspace/builds/worker-4/source
[INFO] validating manifest of crates.io crate tokio-lk 0.2.2 on toolchain 1.49.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate tokio-lk 0.2.2
[INFO] finished tweaking crates.io crate tokio-lk 0.2.2
[INFO] tweaked toml for crates.io crate tokio-lk 0.2.2 written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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" "rustops/crates-build-env@sha256:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] cb03c83ec2b33a99bef591fb1643619ac05fbade9673d7e1d168dfb4a1b88a2d
[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" "cb03c83ec2b33a99bef591fb1643619ac05fbade9673d7e1d168dfb4a1b88a2d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "cb03c83ec2b33a99bef591fb1643619ac05fbade9673d7e1d168dfb4a1b88a2d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "cb03c83ec2b33a99bef591fb1643619ac05fbade9673d7e1d168dfb4a1b88a2d", kill_on_drop: false }`
[INFO] [stdout] cb03c83ec2b33a99bef591fb1643619ac05fbade9673d7e1d168dfb4a1b88a2d
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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" "rustops/crates-build-env@sha256:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 5dbe8b2e95da130e854cad666f5f57da49ed69f00fbf091c0355356a6cbdbbfd
[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" "5dbe8b2e95da130e854cad666f5f57da49ed69f00fbf091c0355356a6cbdbbfd", kill_on_drop: false }`
[INFO] [stderr]    Compiling tiny-keccak v2.0.2
[INFO] [stderr]    Compiling hashbrown v0.7.2
[INFO] [stderr]    Compiling getrandom v0.2.1
[INFO] [stderr]    Compiling tokio-macros v0.2.6
[INFO] [stderr]    Compiling futures-util v0.3.8
[INFO] [stderr]    Compiling const-random-macro v0.1.13
[INFO] [stderr]    Compiling const-random v0.1.13
[INFO] [stderr]    Compiling ahash v0.3.8
[INFO] [stderr]    Compiling tokio v0.2.24
[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/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`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "5dbe8b2e95da130e854cad666f5f57da49ed69f00fbf091c0355356a6cbdbbfd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5dbe8b2e95da130e854cad666f5f57da49ed69f00fbf091c0355356a6cbdbbfd", kill_on_drop: false }`
[INFO] [stdout] 5dbe8b2e95da130e854cad666f5f57da49ed69f00fbf091c0355356a6cbdbbfd