[INFO] fetching crate label 0.6.0...
[INFO] testing label-0.6.0 against 1.90.0 for beta-1.91-3
[INFO] extracting crate label 0.6.0 into /workspace/builds/worker-4-tc1/source
[INFO] started tweaking crates.io crate label 0.6.0
[INFO] finished tweaking crates.io crate label 0.6.0
[INFO] tweaked toml for crates.io crate label 0.6.0 written to /workspace/builds/worker-4-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate label 0.6.0 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] crate crates.io crate label 0.6.0 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] [stderr]     Updating crates.io index
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded ctor v0.1.15
[INFO] [stderr]   Downloaded label-macros v0.6.0
[INFO] [stderr]   Downloaded proc-macro2 v1.0.18
[INFO] [stderr]   Downloaded syn v1.0.33
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-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] a20d9ea9307217606464577ae2a81b16c54cc1a71d8aeb280546b5d97ffcae66
[INFO] running `Command { std: "docker" "start" "-a" "a20d9ea9307217606464577ae2a81b16c54cc1a71d8aeb280546b5d97ffcae66", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "a20d9ea9307217606464577ae2a81b16c54cc1a71d8aeb280546b5d97ffcae66", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a20d9ea9307217606464577ae2a81b16c54cc1a71d8aeb280546b5d97ffcae66", kill_on_drop: false }`
[INFO] [stdout] a20d9ea9307217606464577ae2a81b16c54cc1a71d8aeb280546b5d97ffcae66
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-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] b48a84d2c1b5917cc66dc252c7b0ed955b4bb6b9922c3fb6820ebe0f46f0b036
[INFO] running `Command { std: "docker" "start" "-a" "b48a84d2c1b5917cc66dc252c7b0ed955b4bb6b9922c3fb6820ebe0f46f0b036", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.18
[INFO] [stderr]    Compiling unicode-xid v0.2.1
[INFO] [stderr]    Compiling syn v1.0.33
[INFO] [stderr]    Compiling quote v1.0.7
[INFO] [stderr]    Compiling ctor v0.1.15
[INFO] [stderr]    Compiling label-macros v0.6.0
[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/label-macros-0.6.0/src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(proc_macro_span)]
[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 `label-macros` (lib) due to 1 previous error
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] running `Command { std: "docker" "inspect" "b48a84d2c1b5917cc66dc252c7b0ed955b4bb6b9922c3fb6820ebe0f46f0b036", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b48a84d2c1b5917cc66dc252c7b0ed955b4bb6b9922c3fb6820ebe0f46f0b036", kill_on_drop: false }`
[INFO] [stdout] b48a84d2c1b5917cc66dc252c7b0ed955b4bb6b9922c3fb6820ebe0f46f0b036