[INFO] updating cached repository https://github.com/usbalbin/neural_network
[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] 8756dcd64ef0e5b239264f59ef5f6951d9494d4b
[INFO] testing usbalbin/neural_network against beta-2019-09-28 for beta-1.39-1
[INFO] running `"git" "clone" "work/cache/git-repos/https%3A%2F%2Fgithub.com%2Fusbalbin%2Fneural_network" "work/builds/worker-3/source"`
[INFO] [stderr] Cloning into 'work/builds/worker-3/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/usbalbin/neural_network 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 git repo https://github.com/usbalbin/neural_network
[INFO] finished tweaking git repo https://github.com/usbalbin/neural_network
[INFO] tweaked toml for git repo https://github.com/usbalbin/neural_network written to work/builds/worker-3/source/Cargo.toml
[INFO] crate git repo https://github.com/usbalbin/neural_network already has a lockfile, it will not be regenerated
[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-3/target:/opt/rustwide/target:rw,Z" "-v" "/big/crater/work/builds/worker-3/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] 7ca14934f3924097abca901422e08b05f0f0c7d8ae52bbc74fcd0bc2853416ed
[INFO] running `"docker" "start" "-a" "7ca14934f3924097abca901422e08b05f0f0c7d8ae52bbc74fcd0bc2853416ed"`
[INFO] [stderr]    Compiling libc v0.2.34
[INFO] [stderr]    Compiling linear_algebra v0.1.5 (https://github.com/usbalbin/linear_algebra.git#4f5a6b80)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stderr]  --> /opt/rustwide/cargo-home/git/checkouts/linear_algebra-aed142029d91cb17/4f5a6b8/src/lib.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(iterator_step_by)]
[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 `linear_algebra`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "7ca14934f3924097abca901422e08b05f0f0c7d8ae52bbc74fcd0bc2853416ed"`
[INFO] running `"docker" "rm" "-f" "7ca14934f3924097abca901422e08b05f0f0c7d8ae52bbc74fcd0bc2853416ed"`
[INFO] [stdout] 7ca14934f3924097abca901422e08b05f0f0c7d8ae52bbc74fcd0bc2853416ed