[INFO] updating cached repository https://github.com/utkuce/wav2midi
[INFO] running `"git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/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] b47714f3ecc3b347e5b72e7742f063b1a82e8941
[INFO] checking utkuce/wav2midi against beta-2019-10-27 for pr-65897
[INFO] running `"git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Futkuce%2Fwav2midi" "/workspace/builds/worker-4/source"`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/utkuce/wav2midi on toolchain beta-2019-10-27
[INFO] running `"/workspace/cargo-home/bin/cargo" "+beta-2019-10-27" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking git repo https://github.com/utkuce/wav2midi
[INFO] finished tweaking git repo https://github.com/utkuce/wav2midi
[INFO] tweaked toml for git repo https://github.com/utkuce/wav2midi written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] running `"/workspace/cargo-home/bin/cargo" "+beta-2019-10-27" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] [stderr]     Updating git repository `https://github.com/gyng/synthrs`
[INFO] running `"/workspace/cargo-home/bin/cargo" "+beta-2019-10-27" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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" "MAP_USER_ID=0" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=allow" "-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-2019-10-27" "check" "--frozen" "--all" "--all-targets"`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 73cbe96a55e8016c8ebe482061bc1179304857670fea82f57c844b64d224f631
[INFO] running `"docker" "start" "-a" "73cbe96a55e8016c8ebe482061bc1179304857670fea82f57c844b64d224f631"`
[INFO] [stderr]     Checking apodize v1.0.0
[INFO] [stderr]     Checking num v0.2.0
[INFO] [stderr]    Compiling arrayfire v3.6.2
[INFO] [stderr]     Checking rimd v0.0.1
[INFO] [stderr]     Checking synthrs v0.1.0 (https://github.com/gyng/synthrs#1e5573c3)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stderr]  --> /opt/rustwide/cargo-home/git/checkouts/synthrs-a4b8c03c849616c3/1e5573c/src/lib.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(fn_traits, unboxed_closures)]
[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 `synthrs`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "73cbe96a55e8016c8ebe482061bc1179304857670fea82f57c844b64d224f631"`
[INFO] running `"docker" "rm" "-f" "73cbe96a55e8016c8ebe482061bc1179304857670fea82f57c844b64d224f631"`
[INFO] [stdout] 73cbe96a55e8016c8ebe482061bc1179304857670fea82f57c844b64d224f631