[INFO] updating cached repository https://github.com/BlockCat/rust-sudoku-solver
[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] 90c18645184d65f96d6b5059f06876efaae0fab4
[INFO] checking BlockCat/rust-sudoku-solver against beta-2019-10-27 for pr-65897
[INFO] running `"git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FBlockCat%2Frust-sudoku-solver" "/workspace/builds/worker-9/source"`
[INFO] [stderr] Cloning into '/workspace/builds/worker-9/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/BlockCat/rust-sudoku-solver 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/BlockCat/rust-sudoku-solver
[INFO] finished tweaking git repo https://github.com/BlockCat/rust-sudoku-solver
[INFO] tweaked toml for git repo https://github.com/BlockCat/rust-sudoku-solver written to /workspace/builds/worker-9/source/Cargo.toml
[INFO] crate git repo https://github.com/BlockCat/rust-sudoku-solver already has a lockfile, it will not be regenerated
[INFO] running `"/workspace/cargo-home/bin/cargo" "+beta-2019-10-27" "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" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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] 8465761c06f642475d3762767d083fb4f9eecaf1928b52969efbbd58e7baa5b5
[INFO] running `"docker" "start" "-a" "8465761c06f642475d3762767d083fb4f9eecaf1928b52969efbbd58e7baa5b5"`
[INFO] [stderr]    Compiling libc v0.2.54
[INFO] [stderr]    Compiling cc v1.0.36
[INFO] [stderr]    Compiling stacker v0.1.5
[INFO] [stderr]     Checking sudokusolver v0.1.0 (/opt/rustwide/workdir)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stderr]  --> src/lib.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(vec_remove_item)]
[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 `sudokusolver`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stderr]  --> src/lib.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(vec_remove_item)]
[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 `sudokusolver`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "8465761c06f642475d3762767d083fb4f9eecaf1928b52969efbbd58e7baa5b5"`
[INFO] running `"docker" "rm" "-f" "8465761c06f642475d3762767d083fb4f9eecaf1928b52969efbbd58e7baa5b5"`
[INFO] [stdout] 8465761c06f642475d3762767d083fb4f9eecaf1928b52969efbbd58e7baa5b5