[INFO] fetching crate label-macros 0.6.0...
[INFO] documenting label-macros-0.6.0 against beta-2020-08-29 for beta-1.47-rustdoc-1
[INFO] extracting crate label-macros 0.6.0 into /workspace/builds/worker-9/source
[INFO] validating manifest of crates.io crate label-macros 0.6.0 on toolchain beta-2020-08-29
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate label-macros 0.6.0
[INFO] finished tweaking crates.io crate label-macros 0.6.0
[INFO] tweaked toml for crates.io crate label-macros 0.6.0 written to /workspace/builds/worker-9/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2020-08-29" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 2d6c5a096b42ebae7388ef2df2662c5601400a9352a2d800ce326c5b631fd2c6
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "2d6c5a096b42ebae7388ef2df2662c5601400a9352a2d800ce326c5b631fd2c6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "2d6c5a096b42ebae7388ef2df2662c5601400a9352a2d800ce326c5b631fd2c6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2d6c5a096b42ebae7388ef2df2662c5601400a9352a2d800ce326c5b631fd2c6", kill_on_drop: false }`
[INFO] [stdout] 2d6c5a096b42ebae7388ef2df2662c5601400a9352a2d800ce326c5b631fd2c6
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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" "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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2020-08-29" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] d8a22be57849f93946aca2db95ec48b2048aa7898bc71d6fdc45046f9095c18e
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "d8a22be57849f93946aca2db95ec48b2048aa7898bc71d6fdc45046f9095c18e", kill_on_drop: false }`
[INFO] [stderr]    Compiling syn v1.0.39
[INFO] [stderr]  Documenting label-macros v0.6.0 (/opt/rustwide/workdir)
[INFO] [stderr] error: Could not document `label-macros`.
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(proc_macro_span)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] 
[INFO] [stdout] error: Compilation failed, aborting rustdoc
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] Caused by:
[INFO] [stdout] error: aborting due to 2 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type proc-macro --crate-name label_macros src/lib.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi --document-private-items -L dependency=/opt/rustwide/target/debug/deps --extern quote=/opt/rustwide/target/debug/deps/libquote-d9a4b78de3e51155.rmeta --extern syn=/opt/rustwide/target/debug/deps/libsyn-2ab477503e0ea552.rmeta --extern proc_macro --cap-lints=warn --crate-version 0.6.0` (exit code: 1)
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "d8a22be57849f93946aca2db95ec48b2048aa7898bc71d6fdc45046f9095c18e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d8a22be57849f93946aca2db95ec48b2048aa7898bc71d6fdc45046f9095c18e", kill_on_drop: false }`
[INFO] [stdout] d8a22be57849f93946aca2db95ec48b2048aa7898bc71d6fdc45046f9095c18e