[INFO] fetching crate polars_arrow_rvsry99dx 0.17.1...
[INFO] testing polars_arrow_rvsry99dx-0.17.1 against 1.49.0 for beta-1.50-1
[INFO] extracting crate polars_arrow_rvsry99dx 0.17.1 into /workspace/builds/worker-1/source
[INFO] validating manifest of crates.io crate polars_arrow_rvsry99dx 0.17.1 on toolchain 1.49.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate polars_arrow_rvsry99dx 0.17.1
[INFO] finished tweaking crates.io crate polars_arrow_rvsry99dx 0.17.1
[INFO] tweaked toml for crates.io crate polars_arrow_rvsry99dx 0.17.1 written to /workspace/builds/worker-1/source/Cargo.toml
[INFO] crate crates.io crate polars_arrow_rvsry99dx 0.17.1 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "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] fa1348c88dc770d4a3a35acdc5bfbdb63655c8ce4acf588dbcc2913713e61fd8
[INFO] running `Command { std: "docker" "start" "-a" "fa1348c88dc770d4a3a35acdc5bfbdb63655c8ce4acf588dbcc2913713e61fd8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "fa1348c88dc770d4a3a35acdc5bfbdb63655c8ce4acf588dbcc2913713e61fd8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "fa1348c88dc770d4a3a35acdc5bfbdb63655c8ce4acf588dbcc2913713e61fd8", kill_on_drop: false }`
[INFO] [stdout] fa1348c88dc770d4a3a35acdc5bfbdb63655c8ce4acf588dbcc2913713e61fd8
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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" "RUSTFLAGS=--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:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "build" "--frozen" "--message-format=json", 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] 5e12a125f1c831f0eb6e4f4714aed3bd97442dd227ae1b1623a7b5e3df91bc1a
[INFO] running `Command { std: "docker" "start" "-a" "5e12a125f1c831f0eb6e4f4714aed3bd97442dd227ae1b1623a7b5e3df91bc1a", kill_on_drop: false }`
[INFO] [stderr]    Compiling serde v1.0.114
[INFO] [stderr]    Compiling syn v1.0.33
[INFO] [stderr]    Compiling serde_json v1.0.55
[INFO] [stderr]    Compiling encode_unicode v0.3.6
[INFO] [stderr]    Compiling hex v0.4.2
[INFO] [stderr]    Compiling indexmap v1.4.0
[INFO] [stderr]    Compiling flatbuffers v0.6.1
[INFO] [stderr]    Compiling getrandom v0.1.14
[INFO] [stderr]    Compiling dirs v1.0.5
[INFO] [stderr]    Compiling csv-core v0.1.10
[INFO] [stderr]    Compiling regex-automata v0.1.9
[INFO] [stderr]    Compiling chrono v0.4.11
[INFO] [stderr]    Compiling term v0.5.2
[INFO] [stderr]    Compiling rand_core v0.5.1
[INFO] [stderr]    Compiling rand_chacha v0.2.2
[INFO] [stderr]    Compiling rand v0.7.3
[INFO] [stderr]    Compiling bstr v0.2.13
[INFO] [stderr]    Compiling csv v1.1.3
[INFO] [stderr]    Compiling serde_derive v1.0.114
[INFO] [stderr]    Compiling prettytable-rs v0.8.0
[INFO] [stderr]    Compiling polars_arrow_rvsry99dx v0.17.1 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> src/lib.rs:24:1
[INFO] [stdout]    |
[INFO] [stdout] 24 | #![feature(specialization)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
[INFO] [stdout]   --> src/lib.rs:24:12
[INFO] [stdout]    |
[INFO] [stdout] 24 | #![feature(specialization)]
[INFO] [stdout]    |            ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(incomplete_features)]` on by default
[INFO] [stdout]    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
[INFO] [stdout]    = help: consider using `min_specialization` instead, which is more stable and complete
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error; 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `polars_arrow_rvsry99dx`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "5e12a125f1c831f0eb6e4f4714aed3bd97442dd227ae1b1623a7b5e3df91bc1a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5e12a125f1c831f0eb6e4f4714aed3bd97442dd227ae1b1623a7b5e3df91bc1a", kill_on_drop: false }`
[INFO] [stdout] 5e12a125f1c831f0eb6e4f4714aed3bd97442dd227ae1b1623a7b5e3df91bc1a