[INFO] crate dumb-exec 0.0.7 is already in cache
[INFO] testing dumb-exec-0.0.7 against beta-2019-09-28 for beta-1.39-1
[INFO] extracting crate dumb-exec 0.0.7 into work/builds/worker-4/source
[INFO] validating manifest of crates.io crate dumb-exec 0.0.7 on toolchain beta-2019-09-28
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+beta-2019-09-28" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking crates.io crate dumb-exec 0.0.7
[INFO] finished tweaking crates.io crate dumb-exec 0.0.7
[INFO] tweaked toml for crates.io crate dumb-exec 0.0.7 written to work/builds/worker-4/source/Cargo.toml
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+beta-2019-09-28" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+beta-2019-09-28" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[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" "+beta-2019-09-28" "build" "--frozen"`
[INFO] [stdout] 499d4b517f22d20688f7d64d52f78829a352ba741a5dc183f1cfa194c7962a2a
[INFO] running `"docker" "start" "-a" "499d4b517f22d20688f7d64d52f78829a352ba741a5dc183f1cfa194c7962a2a"`
[INFO] [stderr]    Compiling spin v0.4.10
[INFO] [stderr]    Compiling futures-util-preview v0.3.0-alpha.18
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stderr]  --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/spin-0.4.10/src/lib.rs:6:35
[INFO] [stderr]   |
[INFO] [stderr] 6 | #![cfg_attr(feature = "const_fn", feature(const_fn))]
[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 `spin`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "499d4b517f22d20688f7d64d52f78829a352ba741a5dc183f1cfa194c7962a2a"`
[INFO] running `"docker" "rm" "-f" "499d4b517f22d20688f7d64d52f78829a352ba741a5dc183f1cfa194c7962a2a"`
[INFO] [stdout] 499d4b517f22d20688f7d64d52f78829a352ba741a5dc183f1cfa194c7962a2a