[INFO] fetching crate mech-stats 0.2.59...
[INFO] testing mech-stats-0.2.59 against 1.90.0 for beta-1.91-3
[INFO] extracting crate mech-stats 0.2.59 into /workspace/builds/worker-1-tc1/source
[INFO] started tweaking crates.io crate mech-stats 0.2.59
[INFO] finished tweaking crates.io crate mech-stats 0.2.59
[INFO] tweaked toml for crates.io crate mech-stats 0.2.59 written to /workspace/builds/worker-1-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate mech-stats 0.2.59 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] crate crates.io crate mech-stats 0.2.59 already has a lockfile, it will not be regenerated
[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-1-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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] d9d1a0cd10c1d7413671dfa71bd5a53c4d570ed66fd41eda356147c2c7274ed6
[INFO] running `Command { std: "docker" "start" "-a" "d9d1a0cd10c1d7413671dfa71bd5a53c4d570ed66fd41eda356147c2c7274ed6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "d9d1a0cd10c1d7413671dfa71bd5a53c4d570ed66fd41eda356147c2c7274ed6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d9d1a0cd10c1d7413671dfa71bd5a53c4d570ed66fd41eda356147c2c7274ed6", kill_on_drop: false }`
[INFO] [stdout] d9d1a0cd10c1d7413671dfa71bd5a53c4d570ed66fd41eda356147c2c7274ed6
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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] 7f5cc1fd152e0b570c209b3b47e482f8b598b8ceec8a370c83dd7cab8edf340f
[INFO] running `Command { std: "docker" "start" "-a" "7f5cc1fd152e0b570c209b3b47e482f8b598b8ceec8a370c83dd7cab8edf340f", kill_on_drop: false }`
[INFO] [stderr]    Compiling serde v1.0.219
[INFO] [stderr]    Compiling virtue v0.0.18
[INFO] [stderr]    Compiling bytecount v0.6.9
[INFO] [stderr]    Compiling num-traits v0.2.19
[INFO] [stderr]    Compiling unty v0.0.4
[INFO] [stderr]    Compiling syn v2.0.104
[INFO] [stderr]    Compiling brotli v8.0.1
[INFO] [stderr]    Compiling papergrid v0.14.0
[INFO] [stderr]    Compiling bincode_derive v2.0.1
[INFO] [stderr]    Compiling num-integer v0.1.46
[INFO] [stderr]    Compiling approx v0.5.1
[INFO] [stderr]    Compiling num-complex v0.4.6
[INFO] [stderr]    Compiling num-bigint v0.4.6
[INFO] [stderr]    Compiling simba v0.9.0
[INFO] [stderr]    Compiling num-rational v0.4.2
[INFO] [stderr]    Compiling proc-macro-error2 v2.0.1
[INFO] [stderr]    Compiling serde_derive v1.0.219
[INFO] [stderr]    Compiling nalgebra-macros v0.3.0
[INFO] [stderr]    Compiling tabled_derive v0.10.0
[INFO] [stderr]    Compiling tabled v0.18.0
[INFO] [stderr]    Compiling nalgebra v0.34.0
[INFO] [stderr]    Compiling indexmap v2.10.0
[INFO] [stderr]    Compiling serde_json v1.0.142
[INFO] [stderr]    Compiling bincode v2.0.1
[INFO] [stderr]    Compiling mech-core v0.2.59
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/mech-core-0.2.59/src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(get_mut_unchecked)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/mech-core-0.2.59/src/lib.rs:4:1
[INFO] [stdout]   |
[INFO] [stdout] 4 | #![feature(iter_intersperse)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/mech-core-0.2.59/src/lib.rs:5:1
[INFO] [stdout]   |
[INFO] [stdout] 5 | #![feature(extract_if)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/mech-core-0.2.59/src/lib.rs:7:1
[INFO] [stdout]   |
[INFO] [stdout] 7 | #![feature(step_trait)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/mech-core-0.2.59/src/lib.rs:8:1
[INFO] [stdout]   |
[INFO] [stdout] 8 | #![feature(box_patterns)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `mech-core` (lib) due to 5 previous errors
[INFO] running `Command { std: "docker" "inspect" "7f5cc1fd152e0b570c209b3b47e482f8b598b8ceec8a370c83dd7cab8edf340f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7f5cc1fd152e0b570c209b3b47e482f8b598b8ceec8a370c83dd7cab8edf340f", kill_on_drop: false }`
[INFO] [stdout] 7f5cc1fd152e0b570c209b3b47e482f8b598b8ceec8a370c83dd7cab8edf340f