[INFO] updating cached repository https://github.com/yuu/rust-future-example
[INFO] running `"git" "-c" "credential.helper=" "-c" "credential.helper=/big/crater/work/cargo-home/bin/git-credential-null" "-c" "remote.origin.fetch=refs/heads/*:refs/heads/*" "fetch" "origin" "--force" "--prune"`
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] c5704fd681f1180c6d45ceaf720eccd7d1e0247b
[INFO] testing yuu/rust-future-example against 1.38.0 for beta-1.39-1
[INFO] running `"git" "clone" "work/cache/git-repos/https%3A%2F%2Fgithub.com%2Fyuu%2Frust-future-example" "work/builds/worker-4/source"`
[INFO] [stderr] Cloning into 'work/builds/worker-4/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/yuu/rust-future-example on toolchain 1.38.0
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[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 work/builds/worker-4/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 `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `"docker" "create" "-v" "/big/crater/work/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/big/crater/work/builds/worker-4/source:/opt/rustwide/workdir:ro,Z" "-v" "/big/crater/work/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/big/crater/work/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "MAP_USER_ID=1000" "-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" "--network" "none" "rustops/crates-build-env" "/opt/rustwide/cargo-home/bin/cargo" "+1.38.0" "build" "--frozen"`
[INFO] [stdout] 9ffd6aecda7f9c492a77f757def4fe388b96882454ac10c54c212ca3eadcd8b2
[INFO] running `"docker" "start" "-a" "9ffd6aecda7f9c492a77f757def4fe388b96882454ac10c54c212ca3eadcd8b2"`
[INFO] [stderr]    Compiling futures-core-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling syn v0.15.40
[INFO] [stderr]    Compiling async-util v0.1.0 (https://github.com/tokio-rs/async#e1b3ba3d)
[INFO] [stderr]    Compiling arc-waker v0.1.0 (https://github.com/tokio-rs/async#e1b3ba3d)
[INFO] [stderr]    Compiling lock_api v0.3.1
[INFO] [stderr]    Compiling crossbeam-utils v0.6.5 (https://github.com/stjepang/crossbeam?branch=raw-parker#e2a7760f)
[INFO] [stderr]    Compiling tracing-core v0.1.2
[INFO] [stderr]    Compiling parking_lot_core v0.6.1
[INFO] [stderr]    Compiling parking_lot v0.9.0
[INFO] [stderr]    Compiling crossbeam-epoch v0.7.1
[INFO] [stderr]    Compiling bytes v0.4.12
[INFO] [stderr]    Compiling mio-uds v0.6.7
[INFO] [stderr]    Compiling tokio-executor v0.2.0 (https://github.com/tokio-rs/tokio#e88d10a3)
[INFO] [stderr]    Compiling futures-sink-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling crossbeam-deque v0.7.1
[INFO] [stderr]    Compiling tokio-io v0.2.0 (https://github.com/tokio-rs/tokio#e88d10a3)
[INFO] [stderr]    Compiling tokio-sync v0.2.0 (https://github.com/tokio-rs/tokio#e88d10a3)
[INFO] [stderr]    Compiling tokio-current-thread v0.2.0 (https://github.com/tokio-rs/tokio#e88d10a3)
[INFO] [stderr]    Compiling tokio-codec v0.2.0 (https://github.com/tokio-rs/tokio#e88d10a3)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stderr]   --> /opt/rustwide/cargo-home/git/checkouts/tokio-377c595163f99a10/e88d10a/tokio-sync/src/lib.rs:10:1
[INFO] [stderr]    |
[INFO] [stderr] 10 | #![feature(async_await)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0554`.
[INFO] [stderr] error: Could not compile `tokio-sync`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "9ffd6aecda7f9c492a77f757def4fe388b96882454ac10c54c212ca3eadcd8b2"`
[INFO] running `"docker" "rm" "-f" "9ffd6aecda7f9c492a77f757def4fe388b96882454ac10c54c212ca3eadcd8b2"`
[INFO] [stdout] 9ffd6aecda7f9c492a77f757def4fe388b96882454ac10c54c212ca3eadcd8b2