[INFO] cloning repository https://github.com/yuu/rust-future-example
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/yuu/rust-future-example" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fyuu%2Frust-future-example", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fyuu%2Frust-future-example'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] c5704fd681f1180c6d45ceaf720eccd7d1e0247b
[INFO] documenting yuu/rust-future-example against 1.46.0 for beta-1.47-rustdoc-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fyuu%2Frust-future-example" "/workspace/builds/worker-1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/yuu/rust-future-example on toolchain 1.46.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.46.0" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/yuu/rust-future-example
[INFO] finished tweaking git repo https://github.com/yuu/rust-future-example
[INFO] tweaked toml for git repo https://github.com/yuu/rust-future-example written to /workspace/builds/worker-1/source/Cargo.toml
[INFO] crate git repo https://github.com/yuu/rust-future-example already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.46.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+1.46.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] e2e6bbd006fe42134e60182f6928db9a00345ad14706f1be8eaedc942b413013
[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" "e2e6bbd006fe42134e60182f6928db9a00345ad14706f1be8eaedc942b413013", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "e2e6bbd006fe42134e60182f6928db9a00345ad14706f1be8eaedc942b413013", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e2e6bbd006fe42134e60182f6928db9a00345ad14706f1be8eaedc942b413013", kill_on_drop: false }`
[INFO] [stdout] e2e6bbd006fe42134e60182f6928db9a00345ad14706f1be8eaedc942b413013
[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" "RUSTDOCFLAGS=--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:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+1.46.0" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 009871d64129223981608895745502bc33b4bbdfb0234c1d1a58e0477f4ad54e
[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" "009871d64129223981608895745502bc33b4bbdfb0234c1d1a58e0477f4ad54e", kill_on_drop: false }`
[INFO] [stderr]     Checking futures-core-preview v0.3.0-alpha.17
[INFO] [stderr]     Checking async-util v0.1.0 (https://github.com/tokio-rs/async#e1b3ba3d)
[INFO] [stderr]    Compiling syn v0.15.40
[INFO] [stderr]     Checking arc-waker v0.1.0 (https://github.com/tokio-rs/async#e1b3ba3d)
[INFO] [stderr]     Checking crossbeam-utils v0.6.5 (https://github.com/stjepang/crossbeam?branch=raw-parker#e2a7760f)
[INFO] [stderr]     Checking tracing-core v0.1.2
[INFO] [stderr]     Checking crossbeam-channel v0.3.8
[INFO] [stderr]    Compiling parking_lot_core v0.6.1
[INFO] [stderr]     Checking crossbeam-epoch v0.7.1
[INFO] [stderr]     Checking bytes v0.4.12
[INFO] [stderr]     Checking mio-uds v0.6.7
[INFO] [stderr]     Checking futures-sink-preview v0.3.0-alpha.17
[INFO] [stderr]     Checking tokio-sync v0.2.0 (https://github.com/tokio-rs/tokio#e88d10a3)
[INFO] [stderr]     Checking crossbeam-deque v0.7.1
[INFO] [stderr]     Checking tokio-executor v0.2.0 (https://github.com/tokio-rs/tokio#e88d10a3)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> /opt/rustwide/cargo-home/git/checkouts/tokio-377c595163f99a10/e88d10a/tokio-sync/src/lib.rs:10:1
[INFO] [stdout]    |
[INFO] [stdout] 10 | #![feature(async_await)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Checking tokio-io v0.2.0 (https://github.com/tokio-rs/tokio#e88d10a3)
[INFO] [stderr]     Checking tokio-codec v0.2.0 (https://github.com/tokio-rs/tokio#e88d10a3)
[INFO] [stderr]     Checking parking_lot v0.9.0
[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 `tokio-sync`.
[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" "009871d64129223981608895745502bc33b4bbdfb0234c1d1a58e0477f4ad54e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "009871d64129223981608895745502bc33b4bbdfb0234c1d1a58e0477f4ad54e", kill_on_drop: false }`
[INFO] [stdout] 009871d64129223981608895745502bc33b4bbdfb0234c1d1a58e0477f4ad54e