[INFO] crate un_algebra 0.9.0 is already in cache
[INFO] testing un_algebra-0.9.0 against beta-2020-06-03 for beta-1.45-1
[INFO] extracting crate un_algebra 0.9.0 into /workspace/builds/worker-7/source
[INFO] validating manifest of crates.io crate un_algebra 0.9.0 on toolchain beta-2020-06-03
[INFO] running `"/workspace/cargo-home/bin/cargo" "+beta-2020-06-03" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking crates.io crate un_algebra 0.9.0
[INFO] finished tweaking crates.io crate un_algebra 0.9.0
[INFO] tweaked toml for crates.io crate un_algebra 0.9.0 written to /workspace/builds/worker-7/source/Cargo.toml
[INFO] crate crates.io crate un_algebra 0.9.0 already has a lockfile, it will not be regenerated
[INFO] running `"/workspace/cargo-home/bin/cargo" "+beta-2020-06-03" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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=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-2020-06-03" "build" "--frozen"`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 0a6990a0a45c72531551ad4fa0be31b74a38b4f28876fc3a34670f5e49c2967d
[INFO] running `"docker" "start" "-a" "0a6990a0a45c72531551ad4fa0be31b74a38b4f28876fc3a34670f5e49c2967d"`
[INFO] [stderr] sudo: setrlimit(RLIMIT_CORE): Operation not permitted
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling byteorder v1.3.2
[INFO] [stderr]    Compiling regex-syntax v0.6.12
[INFO] [stderr]    Compiling num-traits v0.2.10
[INFO] [stderr]    Compiling num-bigint v0.2.3
[INFO] [stderr]    Compiling num-complex v0.2.3
[INFO] [stderr]    Compiling num-iter v0.1.39
[INFO] [stderr]    Compiling num-rational v0.2.2
[INFO] [stderr]    Compiling wait-timeout v0.2.0
[INFO] [stderr]    Compiling tempfile v3.1.0
[INFO] [stderr]    Compiling rand v0.6.5
[INFO] [stderr]    Compiling rusty-fork v0.2.2
[INFO] [stderr]    Compiling num-integer v0.1.41
[INFO] [stderr]    Compiling proptest v0.9.4
[INFO] [stderr]    Compiling num v0.2.0
[INFO] [stderr]    Compiling proptest-derive v0.1.2
[INFO] [stderr]    Compiling un_algebra v0.9.0 (/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(external_doc)]
[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 `un_algebra`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "0a6990a0a45c72531551ad4fa0be31b74a38b4f28876fc3a34670f5e49c2967d"`
[INFO] running `"docker" "rm" "-f" "0a6990a0a45c72531551ad4fa0be31b74a38b4f28876fc3a34670f5e49c2967d"`
[INFO] [stdout] 0a6990a0a45c72531551ad4fa0be31b74a38b4f28876fc3a34670f5e49c2967d