[INFO] updating cached repository https://github.com/motecshine/hello_world
[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] 287eca7f17b361b21acdadabc051f55b80dc578f
[INFO] testing motecshine/hello_world against 1.38.0 for beta-1.39-1
[INFO] running `"git" "clone" "work/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmotecshine%2Fhello_world" "work/builds/worker-0/source"`
[INFO] [stderr] Cloning into 'work/builds/worker-0/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/motecshine/hello_world 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/motecshine/hello_world
[INFO] finished tweaking git repo https://github.com/motecshine/hello_world
[INFO] tweaked toml for git repo https://github.com/motecshine/hello_world written to work/builds/worker-0/source/Cargo.toml
[INFO] crate git repo https://github.com/motecshine/hello_world 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] running `"docker" "create" "-v" "/big/crater/work/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/big/crater/work/builds/worker-0/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] 931b0a410e1a69915a8f60c98c0f6cbbf5ca13f691fde2fa096e8047ed32df06
[INFO] running `"docker" "start" "-a" "931b0a410e1a69915a8f60c98c0f6cbbf5ca13f691fde2fa096e8047ed32df06"`
[INFO] [stderr]    Compiling syn v0.15.38
[INFO] [stderr]    Compiling futures-core-preview v0.3.0-alpha.16
[INFO] [stderr]    Compiling proc-macro-nested v0.1.3
[INFO] [stderr]    Compiling pin-utils v0.1.0-alpha.4
[INFO] [stderr]    Compiling rand_core v0.3.1
[INFO] [stderr]    Compiling num_cpus v1.10.1
[INFO] [stderr]    Compiling rand_hc v0.1.0
[INFO] [stderr]    Compiling rand_xorshift v0.1.1
[INFO] [stderr]    Compiling rand_isaac v0.1.1
[INFO] [stderr]    Compiling rand_chacha v0.1.1
[INFO] [stderr]    Compiling futures-channel-preview v0.3.0-alpha.16
[INFO] [stderr]    Compiling futures-io-preview v0.3.0-alpha.16
[INFO] [stderr]    Compiling rand v0.6.5
[INFO] [stderr]    Compiling futures-sink-preview v0.3.0-alpha.16
[INFO] [stderr]    Compiling proc-macro-hack v0.5.7
[INFO] [stderr]    Compiling futures-select-macro-preview v0.3.0-alpha.16
[INFO] [stderr]    Compiling futures-util-preview v0.3.0-alpha.16
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stderr]  --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/futures-util-preview-0.3.0-alpha.16/src/lib.rs:4:38
[INFO] [stderr]   |
[INFO] [stderr] 4 | #![cfg_attr(feature = "async-await", 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 `futures-util-preview`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "931b0a410e1a69915a8f60c98c0f6cbbf5ca13f691fde2fa096e8047ed32df06"`
[INFO] running `"docker" "rm" "-f" "931b0a410e1a69915a8f60c98c0f6cbbf5ca13f691fde2fa096e8047ed32df06"`
[INFO] [stdout] 931b0a410e1a69915a8f60c98c0f6cbbf5ca13f691fde2fa096e8047ed32df06