[INFO] fetching crate polars 0.4.0...
[INFO] documenting polars-0.4.0 against beta-2020-08-29 for beta-1.47-rustdoc-1
[INFO] extracting crate polars 0.4.0 into /workspace/builds/worker-7/source
[INFO] validating manifest of crates.io crate polars 0.4.0 on toolchain beta-2020-08-29
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate polars 0.4.0
[INFO] finished tweaking crates.io crate polars 0.4.0
[INFO] tweaked toml for crates.io crate polars 0.4.0 written to /workspace/builds/worker-7/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded enum_dispatch v0.3.2
[INFO] [stderr]   Downloaded arrow v1.0.1
[INFO] [stderr]   Downloaded unsafe_unwrap v0.1.0
[INFO] running `Command { std: "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" "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" "--user" "0:0" "--network" "none" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2020-08-29" "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] 2c9cc246eb57be8348fc91b586c730421e9879e1fc2fc0ede63e6af38ffb27c8
[INFO] running `Command { std: "docker" "start" "-a" "2c9cc246eb57be8348fc91b586c730421e9879e1fc2fc0ede63e6af38ffb27c8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "2c9cc246eb57be8348fc91b586c730421e9879e1fc2fc0ede63e6af38ffb27c8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2c9cc246eb57be8348fc91b586c730421e9879e1fc2fc0ede63e6af38ffb27c8", kill_on_drop: false }`
[INFO] [stdout] 2c9cc246eb57be8348fc91b586c730421e9879e1fc2fc0ede63e6af38ffb27c8
[INFO] running `Command { std: "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" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTDOCFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2020-08-29" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 980b2e89c7da8d5156ac918525c1a4d29a8d3a140447c1b7ea7e6b3a027773ec
[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" "980b2e89c7da8d5156ac918525c1a4d29a8d3a140447c1b7ea7e6b3a027773ec", kill_on_drop: false }`
[INFO] [stderr]     Checking encode_unicode v0.3.6
[INFO] [stderr]    Compiling once_cell v1.4.1
[INFO] [stderr]     Checking unsafe_unwrap v0.1.0
[INFO] [stderr]    Compiling num-traits v0.2.12
[INFO] [stderr]    Compiling num-integer v0.1.43
[INFO] [stderr]    Compiling num-iter v0.1.41
[INFO] [stderr]     Checking flatbuffers v0.6.1
[INFO] [stderr]     Checking csv-core v0.1.10
[INFO] [stderr]     Checking regex-automata v0.1.9
[INFO] [stderr]     Checking term v0.5.2
[INFO] [stderr]    Compiling thiserror-impl v1.0.20
[INFO] [stderr]     Checking serde_json v1.0.57
[INFO] [stderr]     Checking crossbeam v0.7.3
[INFO] [stderr]    Compiling enum_dispatch v0.3.2
[INFO] [stderr]     Checking bstr v0.2.13
[INFO] [stderr]     Checking prettytable-rs v0.8.0
[INFO] [stderr]     Checking csv v1.1.3
[INFO] [stderr]     Checking num-complex v0.3.0
[INFO] [stderr]     Checking num-complex v0.2.4
[INFO] [stderr]     Checking num-bigint v0.3.0
[INFO] [stderr]     Checking num-bigint v0.2.6
[INFO] [stderr]     Checking chrono v0.4.15
[INFO] [stderr]     Checking thiserror v1.0.20
[INFO] [stderr]     Checking num-rational v0.2.4
[INFO] [stderr]     Checking num-rational v0.3.0
[INFO] [stderr]     Checking num v0.2.1
[INFO] [stderr]     Checking num v0.3.0
[INFO] [stderr]     Checking arrow v1.0.1
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]   --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/arrow-1.0.1/src/lib.rs:24:1
[INFO] [stdout]    |
[INFO] [stdout] 24 | #![feature(specialization)]
[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 `arrow`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "980b2e89c7da8d5156ac918525c1a4d29a8d3a140447c1b7ea7e6b3a027773ec", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "980b2e89c7da8d5156ac918525c1a4d29a8d3a140447c1b7ea7e6b3a027773ec", kill_on_drop: false }`
[INFO] [stdout] 980b2e89c7da8d5156ac918525c1a4d29a8d3a140447c1b7ea7e6b3a027773ec