[INFO] cloning repository https://github.com/LooMaclin/tux_async_example
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/LooMaclin/tux_async_example" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FLooMaclin%2Ftux_async_example", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FLooMaclin%2Ftux_async_example'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] a42870d0c2d19a9213a03f4c191909d2cce56a64
[INFO] documenting LooMaclin/tux_async_example against beta-2020-08-29 for beta-1.47-rustdoc-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FLooMaclin%2Ftux_async_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/LooMaclin/tux_async_example on toolchain beta-2020-08-29
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/LooMaclin/tux_async_example
[INFO] finished tweaking git repo https://github.com/LooMaclin/tux_async_example
[INFO] tweaked toml for git repo https://github.com/LooMaclin/tux_async_example written to /workspace/builds/worker-1/source/Cargo.toml
[INFO] crate git repo https://github.com/LooMaclin/tux_async_example already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded tokio-async-await v0.1.5
[INFO] [stderr]   Downloaded tokio v0.1.15
[INFO] [stderr]   Downloaded tokio-threadpool v0.1.11
[INFO] [stderr]   Downloaded tokio-io v0.1.11
[INFO] [stderr]   Downloaded tokio-sync v0.1.1
[INFO] [stderr]   Downloaded tokio-reactor v0.1.8
[INFO] [stderr]   Downloaded tokio-fs v0.1.5
[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" "+beta-2020-08-29" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 3dadd1d6be2a09f1622169eba42ecf795e4e0cd40c878c3da6405c0b28e395f7
[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" "3dadd1d6be2a09f1622169eba42ecf795e4e0cd40c878c3da6405c0b28e395f7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "3dadd1d6be2a09f1622169eba42ecf795e4e0cd40c878c3da6405c0b28e395f7", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "3dadd1d6be2a09f1622169eba42ecf795e4e0cd40c878c3da6405c0b28e395f7", kill_on_drop: false }`
[INFO] [stdout] 3dadd1d6be2a09f1622169eba42ecf795e4e0cd40c878c3da6405c0b28e395f7
[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" "+beta-2020-08-29" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 1a8e37ad43cd207332183b1b449bbed976bdf6c495312a9683743811ff4853e3
[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" "1a8e37ad43cd207332183b1b449bbed976bdf6c495312a9683743811ff4853e3", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling libc v0.2.48
[INFO] [stderr]     Checking futures v0.1.25
[INFO] [stderr]    Compiling byteorder v1.3.1
[INFO] [stderr]    Compiling arrayvec v0.4.10
[INFO] [stderr]     Checking nodrop v0.1.13
[INFO] [stderr]     Checking crossbeam-utils v0.6.5
[INFO] [stderr]     Checking log v0.4.6
[INFO] [stderr]     Checking smallvec v0.6.8
[INFO] [stderr]    Compiling rand_pcg v0.1.1
[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/futures-0.1.25/src/lib.rs:161:34
[INFO] [stdout]     |
[INFO] [stdout] 161 | #![cfg_attr(feature = "nightly", feature(pin))]
[INFO] [stdout]     |                                  ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Checking crossbeam-channel v0.3.8
[INFO] [stderr]     Checking crossbeam-epoch v0.7.1
[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 `futures`.
[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" "1a8e37ad43cd207332183b1b449bbed976bdf6c495312a9683743811ff4853e3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1a8e37ad43cd207332183b1b449bbed976bdf6c495312a9683743811ff4853e3", kill_on_drop: false }`
[INFO] [stdout] 1a8e37ad43cd207332183b1b449bbed976bdf6c495312a9683743811ff4853e3