[INFO] fetching crate un_algebra 0.9.0...
[INFO] testing un_algebra-0.9.0 against beta-2020-07-24 for beta-1.46-1
[INFO] extracting crate un_algebra 0.9.0 into /workspace/builds/worker-0/source
[INFO] validating manifest of crates.io crate un_algebra 0.9.0 on toolchain beta-2020-07-24
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-07-24" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[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-0/source/Cargo.toml
[INFO] crate crates.io crate un_algebra 0.9.0 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-07-24" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--network" "none" "rustops/crates-build-env@sha256:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2020-07-24" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 6c16d6664df3eb1c925303a3ba4f55454922a80fedfffafb2c98862dd3e04523
[INFO] running `Command { std: "docker" "start" "-a" "6c16d6664df3eb1c925303a3ba4f55454922a80fedfffafb2c98862dd3e04523", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "6c16d6664df3eb1c925303a3ba4f55454922a80fedfffafb2c98862dd3e04523", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6c16d6664df3eb1c925303a3ba4f55454922a80fedfffafb2c98862dd3e04523", kill_on_drop: false }`
[INFO] [stdout] 6c16d6664df3eb1c925303a3ba4f55454922a80fedfffafb2c98862dd3e04523
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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@sha256:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2020-07-24" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 1b21bceccc0632876faf84c07819b1818b150712e176e7260bd8a3e81f94c54a
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "1b21bceccc0632876faf84c07819b1818b150712e176e7260bd8a3e81f94c54a", kill_on_drop: false }`
[INFO] [stderr]    Compiling autocfg v0.1.7
[INFO] [stderr]    Compiling libc v0.2.66
[INFO] [stderr]    Compiling rand_core v0.4.2
[INFO] [stderr]    Compiling getrandom v0.1.13
[INFO] [stderr]    Compiling ppv-lite86 v0.2.6
[INFO] [stderr]    Compiling proc-macro2 v0.4.30
[INFO] [stderr]    Compiling unicode-xid v0.1.0
[INFO] [stderr]    Compiling bitflags v1.2.1
[INFO] [stderr]    Compiling byteorder v1.3.2
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling remove_dir_all v0.5.2
[INFO] [stderr]    Compiling quick-error v1.2.2
[INFO] [stderr]    Compiling fnv v1.0.6
[INFO] [stderr]    Compiling bit-vec v0.5.1
[INFO] [stderr]    Compiling lazy_static v1.4.0
[INFO] [stderr]    Compiling regex-syntax v0.6.12
[INFO] [stderr]    Compiling bit-set v0.5.1
[INFO] [stderr]    Compiling rand_core v0.3.1
[INFO] [stderr]    Compiling rand_jitter v0.1.4
[INFO] [stderr]    Compiling rand_hc v0.1.0
[INFO] [stderr]    Compiling rand_isaac v0.1.1
[INFO] [stderr]    Compiling rand_xorshift v0.1.1
[INFO] [stderr]    Compiling num-traits v0.2.10
[INFO] [stderr]    Compiling num-integer v0.1.41
[INFO] [stderr]    Compiling rand_chacha v0.1.1
[INFO] [stderr]    Compiling num-bigint v0.2.3
[INFO] [stderr]    Compiling rand_pcg v0.1.2
[INFO] [stderr]    Compiling num-rational v0.2.2
[INFO] [stderr]    Compiling rand v0.6.5
[INFO] [stderr]    Compiling num-iter v0.1.39
[INFO] [stderr]    Compiling num-complex v0.2.3
[INFO] [stderr]    Compiling c2-chacha v0.2.3
[INFO] [stderr]    Compiling quote v0.6.13
[INFO] [stderr]    Compiling wait-timeout v0.2.0
[INFO] [stderr]    Compiling rand_os v0.1.3
[INFO] [stderr]    Compiling rand_core v0.5.1
[INFO] [stderr]    Compiling rand_chacha v0.2.1
[INFO] [stderr]    Compiling rand v0.7.2
[INFO] [stderr]    Compiling tempfile v3.1.0
[INFO] [stderr]    Compiling rusty-fork v0.2.2
[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] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(external_doc)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `un_algebra`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "1b21bceccc0632876faf84c07819b1818b150712e176e7260bd8a3e81f94c54a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1b21bceccc0632876faf84c07819b1818b150712e176e7260bd8a3e81f94c54a", kill_on_drop: false }`
[INFO] [stdout] 1b21bceccc0632876faf84c07819b1818b150712e176e7260bd8a3e81f94c54a