[INFO] fetching crate kf-protocol-api 2.0.0...
[INFO] testing kf-protocol-api-2.0.0 against 1.90.0 for beta-1.91-3
[INFO] extracting crate kf-protocol-api 2.0.0 into /workspace/builds/worker-3-tc1/source
[INFO] started tweaking crates.io crate kf-protocol-api 2.0.0
[INFO] finished tweaking crates.io crate kf-protocol-api 2.0.0
[INFO] tweaked toml for crates.io crate kf-protocol-api 2.0.0 written to /workspace/builds/worker-3-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate kf-protocol-api 2.0.0 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 77 packages to latest compatible versions
[INFO] [stderr]       Adding crc32c v0.5.0 (available: v0.6.8)
[INFO] [stderr]       Adding flv-util v0.4.0 (available: v0.5.2)
[INFO] [stderr]       Adding paste v0.1.18 (available: v1.0.15)
[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] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded crc32c v0.5.0
[INFO] [stderr]   Downloaded kf-protocol-derive v0.2.0
[INFO] [stderr]   Downloaded content_inspector v0.2.4
[INFO] [stderr]   Downloaded kf-protocol-core v0.1.2
[INFO] [stderr]   Downloaded flv-util v0.4.0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-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] d8e4bb9a818d4bbd9cd8192a937ee0346d9379c18b139915e5fb18a26b9b0dcc
[INFO] running `Command { std: "docker" "start" "-a" "d8e4bb9a818d4bbd9cd8192a937ee0346d9379c18b139915e5fb18a26b9b0dcc", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "d8e4bb9a818d4bbd9cd8192a937ee0346d9379c18b139915e5fb18a26b9b0dcc", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d8e4bb9a818d4bbd9cd8192a937ee0346d9379c18b139915e5fb18a26b9b0dcc", kill_on_drop: false }`
[INFO] [stdout] d8e4bb9a818d4bbd9cd8192a937ee0346d9379c18b139915e5fb18a26b9b0dcc
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-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] bb6d18cb404973fe5f02c76a4f9b35fb66a5018c97edea529fb0da0b21eec5aa
[INFO] running `Command { std: "docker" "start" "-a" "bb6d18cb404973fe5f02c76a4f9b35fb66a5018c97edea529fb0da0b21eec5aa", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v0.4.30
[INFO] [stderr]    Compiling unicode-xid v0.1.0
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling num-derive v0.2.5
[INFO] [stderr]    Compiling matchers v0.0.1
[INFO] [stderr]    Compiling tracing-log v0.1.4
[INFO] [stderr]    Compiling crc32c v0.5.0
[INFO] [stderr]    Compiling tracing-attributes v0.1.30
[INFO] [stderr]    Compiling chrono v0.4.42
[INFO] [stderr]    Compiling content_inspector v0.2.4
[INFO] [stderr]    Compiling kf-protocol-derive v0.2.0
[INFO] [stderr]    Compiling tracing-serde v0.1.3
[INFO] [stderr]    Compiling quote v0.6.13
[INFO] [stderr]    Compiling tracing v0.1.41
[INFO] [stderr]    Compiling tracing-subscriber v0.2.25
[INFO] [stderr]    Compiling flv-util v0.4.0
[INFO] [stderr]    Compiling kf-protocol-core v0.1.2
[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/kf-protocol-core-0.1.2/src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(specialization)]
[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 `kf-protocol-core` (lib) due to 1 previous error
[INFO] running `Command { std: "docker" "inspect" "bb6d18cb404973fe5f02c76a4f9b35fb66a5018c97edea529fb0da0b21eec5aa", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "bb6d18cb404973fe5f02c76a4f9b35fb66a5018c97edea529fb0da0b21eec5aa", kill_on_drop: false }`
[INFO] [stdout] bb6d18cb404973fe5f02c76a4f9b35fb66a5018c97edea529fb0da0b21eec5aa