[INFO] fetching crate kf-protocol-api 2.0.0...
[INFO] testing kf-protocol-api-2.0.0 against 1.55.0 for beta-1.56-1
[INFO] extracting crate kf-protocol-api 2.0.0 into /workspace/builds/worker-24/source
[INFO] validating manifest of crates.io crate kf-protocol-api 2.0.0 on toolchain 1.55.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[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-24/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-24/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-24/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] ac56d4b7242577d6af35bbc79d059be3138e0a6dd0c8b8ebefae3e4dd2afb458
[INFO] running `Command { std: "docker" "start" "-a" "ac56d4b7242577d6af35bbc79d059be3138e0a6dd0c8b8ebefae3e4dd2afb458", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "ac56d4b7242577d6af35bbc79d059be3138e0a6dd0c8b8ebefae3e4dd2afb458", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ac56d4b7242577d6af35bbc79d059be3138e0a6dd0c8b8ebefae3e4dd2afb458", kill_on_drop: false }`
[INFO] [stdout] ac56d4b7242577d6af35bbc79d059be3138e0a6dd0c8b8ebefae3e4dd2afb458
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-24/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-24/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 20124670a6e0f4b20104cfdac93d6a20e49144e1063525865877d621a2601557
[INFO] running `Command { std: "docker" "start" "-a" "20124670a6e0f4b20104cfdac93d6a20e49144e1063525865877d621a2601557", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling proc-macro2 v1.0.29
[INFO] [stderr]    Compiling unicode-xid v0.2.2
[INFO] [stderr]    Compiling syn v1.0.76
[INFO] [stderr]    Compiling serde_derive v1.0.130
[INFO] [stderr]    Compiling log v0.4.14
[INFO] [stderr]    Compiling cfg-if v1.0.0
[INFO] [stderr]    Compiling lazy_static v1.4.0
[INFO] [stderr]    Compiling serde v1.0.130
[INFO] [stderr]    Compiling proc-macro2 v0.4.30
[INFO] [stderr]    Compiling libc v0.2.101
[INFO] [stderr]    Compiling ryu v1.0.5
[INFO] [stderr]    Compiling unicode-xid v0.1.0
[INFO] [stderr]    Compiling regex-syntax v0.6.25
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling proc-macro-hack v0.5.19
[INFO] [stderr]    Compiling serde_json v1.0.67
[INFO] [stderr]    Compiling num-derive v0.2.5
[INFO] [stderr]    Compiling once_cell v1.8.0
[INFO] [stderr]    Compiling memchr v2.4.1
[INFO] [stderr]    Compiling pin-project-lite v0.2.7
[INFO] [stderr]    Compiling itoa v0.4.8
[INFO] [stderr]    Compiling crc32c v0.5.0
[INFO] [stderr]    Compiling smallvec v1.6.1
[INFO] [stderr]    Compiling ansi_term v0.12.1
[INFO] [stderr]    Compiling bytes v0.5.6
[INFO] [stderr]    Compiling num-traits v0.2.14
[INFO] [stderr]    Compiling num-integer v0.1.44
[INFO] [stderr]    Compiling tracing-core v0.1.19
[INFO] [stderr]    Compiling sharded-slab v0.1.3
[INFO] [stderr]    Compiling thread_local v1.1.3
[INFO] [stderr]    Compiling tracing-log v0.1.2
[INFO] [stderr]    Compiling content_inspector v0.2.4
[INFO] [stderr]    Compiling quote v0.6.13
[INFO] [stderr]    Compiling quote v1.0.9
[INFO] [stderr]    Compiling paste-impl v0.1.18
[INFO] [stderr]    Compiling regex-automata v0.1.10
[INFO] [stderr]    Compiling regex v1.5.4
[INFO] [stderr]    Compiling chrono v0.4.19
[INFO] [stderr]    Compiling matchers v0.0.1
[INFO] [stderr]    Compiling paste v0.1.18
[INFO] [stderr]    Compiling tracing-attributes v0.1.15
[INFO] [stderr]    Compiling kf-protocol-derive v0.2.0
[INFO] [stderr]    Compiling tracing v0.1.26
[INFO] [stderr]    Compiling tracing-serde v0.1.2
[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/github.com-1ecc6299db9ec823/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] 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 `kf-protocol-core` due to 2 previous errors
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "20124670a6e0f4b20104cfdac93d6a20e49144e1063525865877d621a2601557", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "20124670a6e0f4b20104cfdac93d6a20e49144e1063525865877d621a2601557", kill_on_drop: false }`
[INFO] [stdout] 20124670a6e0f4b20104cfdac93d6a20e49144e1063525865877d621a2601557