[INFO] fetching crate juliex 0.3.0-alpha.8...
[INFO] documenting juliex-0.3.0-alpha.8 against beta-2020-08-29 for beta-1.47-rustdoc-1
[INFO] extracting crate juliex 0.3.0-alpha.8 into /workspace/builds/worker-11/source
[INFO] validating manifest of crates.io crate juliex 0.3.0-alpha.8 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 crates.io crate juliex 0.3.0-alpha.8
[INFO] finished tweaking crates.io crate juliex 0.3.0-alpha.8
[INFO] tweaked toml for crates.io crate juliex 0.3.0-alpha.8 written to /workspace/builds/worker-11/source/Cargo.toml
[INFO] crate crates.io crate juliex 0.3.0-alpha.8 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 getrandom v0.1.3
[INFO] [stderr]   Downloaded async-ready v2.1.0
[INFO] [stderr]   Downloaded async-datagram v2.2.0
[INFO] [stderr]   Downloaded romio v0.3.0-alpha.7
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-11/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-11/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] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] d26570b987bba87969570cd669ce514874e582a2c17f71a35f825c06caf87687
[INFO] running `Command { std: "docker" "start" "-a" "d26570b987bba87969570cd669ce514874e582a2c17f71a35f825c06caf87687", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "d26570b987bba87969570cd669ce514874e582a2c17f71a35f825c06caf87687", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d26570b987bba87969570cd669ce514874e582a2c17f71a35f825c06caf87687", kill_on_drop: false }`
[INFO] [stdout] d26570b987bba87969570cd669ce514874e582a2c17f71a35f825c06caf87687
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-11/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-11/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] f42c1c844c9e850c146c52bb7350dcf885cbe6d7d7a8701b48321c88b3722a50
[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" "f42c1c844c9e850c146c52bb7350dcf885cbe6d7d7a8701b48321c88b3722a50", kill_on_drop: false }`
[INFO] [stderr]     Checking lazy_static v1.2.0
[INFO] [stderr]    Compiling syn v0.15.34
[INFO] [stderr]    Compiling memchr v2.2.0
[INFO] [stderr]     Checking futures-core-preview v0.3.0-alpha.17
[INFO] [stderr]     Checking futures-io-preview v0.3.0-alpha.17
[INFO] [stderr]     Checking getrandom v0.1.3
[INFO] [stderr]     Checking num_cpus v1.10.0
[INFO] [stderr]     Checking c2-chacha v0.2.2
[INFO] [stderr]     Checking crossbeam-utils v0.6.6
[INFO] [stderr]     Checking futures-sink-preview v0.3.0-alpha.17
[INFO] [stderr]     Checking rand_core v0.5.0
[INFO] [stderr]     Checking futures-channel-preview v0.3.0-alpha.17
[INFO] [stderr]     Checking rand_chacha v0.2.1
[INFO] [stderr]     Checking crossbeam-epoch v0.7.2
[INFO] [stderr]     Checking crossbeam-channel v0.3.9
[INFO] [stderr]     Checking crossbeam-queue v0.1.2
[INFO] [stderr]     Checking rand v0.7.0
[INFO] [stderr]     Checking crossbeam-deque v0.7.1
[INFO] [stderr]     Checking crossbeam v0.7.2
[INFO] [stderr]    Compiling proc-macro-hack v0.5.7
[INFO] [stderr]    Compiling futures-select-macro-preview v0.3.0-alpha.17
[INFO] [stderr]     Checking futures-util-preview v0.3.0-alpha.17
[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-util-preview-0.3.0-alpha.17/src/lib.rs:4:38
[INFO] [stdout]   |
[INFO] [stdout] 4 | #![cfg_attr(feature = "async-await", feature(async_await))]
[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 `futures-util-preview`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "f42c1c844c9e850c146c52bb7350dcf885cbe6d7d7a8701b48321c88b3722a50", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f42c1c844c9e850c146c52bb7350dcf885cbe6d7d7a8701b48321c88b3722a50", kill_on_drop: false }`
[INFO] [stdout] f42c1c844c9e850c146c52bb7350dcf885cbe6d7d7a8701b48321c88b3722a50