[INFO] fetching crate kstd 0.0.4...
[INFO] testing kstd-0.0.4 against 1.90.0 for beta-1.91-3
[INFO] extracting crate kstd 0.0.4 into /workspace/builds/worker-0-tc1/source
[INFO] removed /workspace/builds/worker-0-tc1/source/rust-toolchain.toml
[INFO] started tweaking crates.io crate kstd 0.0.4
[INFO] finished tweaking crates.io crate kstd 0.0.4
[INFO] tweaked toml for crates.io crate kstd 0.0.4 written to /workspace/builds/worker-0-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate kstd 0.0.4 on toolchain 1.90.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 12 packages to latest compatible versions
[INFO] [stderr]       Adding derive_more v0.99.20 (available: v2.0.1)
[INFO] [stderr]       Adding spin v0.9.8 (available: v0.10.0)
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+1.90.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 0b82f7bb31d81e48f28dae9cb3395cff5a66696d40ad1e0f4c2ebb5d43998ba4
[INFO] running `Command { std: "docker" "start" "-a" "0b82f7bb31d81e48f28dae9cb3395cff5a66696d40ad1e0f4c2ebb5d43998ba4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "0b82f7bb31d81e48f28dae9cb3395cff5a66696d40ad1e0f4c2ebb5d43998ba4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0b82f7bb31d81e48f28dae9cb3395cff5a66696d40ad1e0f4c2ebb5d43998ba4", kill_on_drop: false }`
[INFO] [stdout] 0b82f7bb31d81e48f28dae9cb3395cff5a66696d40ad1e0f4c2ebb5d43998ba4
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/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" "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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+1.90.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] e13fa8b004da7ece0edff54502aef4cda0acb9da49dcb05ff5a7a0c15386f9e2
[INFO] running `Command { std: "docker" "start" "-a" "e13fa8b004da7ece0edff54502aef4cda0acb9da49dcb05ff5a7a0c15386f9e2", kill_on_drop: false }`
[INFO] [stderr]    Compiling convert_case v0.4.0
[INFO] [stderr]    Compiling syn v2.0.106
[INFO] [stderr]    Compiling derive_more v0.99.20
[INFO] [stderr]    Compiling kstd v0.0.4 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(error_in_core)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `crate::io::read::*`
[INFO] [stdout]   --> src/io/mod.rs:12:9
[INFO] [stdout]    |
[INFO] [stdout] 12 | pub use crate::io::read::*;
[INFO] [stdout]    |         ^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the feature `error_in_core` has been stable since 1.81.0 and no longer requires an attribute to enable
[INFO] [stdout]  --> src/lib.rs:2:12
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(error_in_core)]
[INFO] [stdout]   |            ^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(stable_features)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `kstd` (lib) due to 1 previous error; 2 warnings emitted
[INFO] running `Command { std: "docker" "inspect" "e13fa8b004da7ece0edff54502aef4cda0acb9da49dcb05ff5a7a0c15386f9e2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e13fa8b004da7ece0edff54502aef4cda0acb9da49dcb05ff5a7a0c15386f9e2", kill_on_drop: false }`
[INFO] [stdout] e13fa8b004da7ece0edff54502aef4cda0acb9da49dcb05ff5a7a0c15386f9e2