[INFO] fetching crate xtra 0.5.0-beta.4...
[INFO] documenting xtra-0.5.0-beta.4 against beta-2020-08-29 for beta-1.47-rustdoc-1
[INFO] extracting crate xtra 0.5.0-beta.4 into /workspace/builds/worker-7/source
[INFO] validating manifest of crates.io crate xtra 0.5.0-beta.4 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 xtra 0.5.0-beta.4
[INFO] removed 0 missing examples
[INFO] finished tweaking crates.io crate xtra 0.5.0-beta.4
[INFO] tweaked toml for crates.io crate xtra 0.5.0-beta.4 written to /workspace/builds/worker-7/source/Cargo.toml
[INFO] crate crates.io crate xtra 0.5.0-beta.4 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2020-08-29" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded async-io v0.1.6
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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] 74ab9260905a110121b9782cadee97458416ad46ff576d333d80bc0d82f01a33
[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" "74ab9260905a110121b9782cadee97458416ad46ff576d333d80bc0d82f01a33", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "74ab9260905a110121b9782cadee97458416ad46ff576d333d80bc0d82f01a33", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "74ab9260905a110121b9782cadee97458416ad46ff576d333d80bc0d82f01a33", kill_on_drop: false }`
[INFO] [stdout] 74ab9260905a110121b9782cadee97458416ad46ff576d333d80bc0d82f01a33
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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] df8a2b478b051b020f457280f148b67bc5de31735991b23689d75d6be201037b
[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" "df8a2b478b051b020f457280f148b67bc5de31735991b23689d75d6be201037b", 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] [stderr]    Compiling syn v1.0.33
[INFO] [stderr]    Compiling pin-project-internal v0.4.22
[INFO] [stderr]    Compiling async-trait v0.1.36
[INFO] [stderr]     Checking pin-project v0.4.22
[INFO] [stderr]     Checking futures-util v0.3.5
[INFO] [stderr]     Checking futures v0.3.5
[INFO] [stderr]  Documenting xtra v0.5.0-beta.4 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/lib.rs:3:18
[INFO] [stdout]   |
[INFO] [stdout] 3 | #![cfg_attr(doc, feature(doc_cfg, external_doc))]
[INFO] [stdout]   |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: Compilation failed, aborting rustdoc
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: Could not document `xtra`.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type lib --crate-name xtra src/lib.rs -o /opt/rustwide/target/doc --cfg 'feature="default"' --error-format=json --json=diagnostic-rendered-ansi --document-private-items -L dependency=/opt/rustwide/target/debug/deps --extern async_trait=/opt/rustwide/target/debug/deps/libasync_trait-a61ce72c3eb87d2a.so --extern futures=/opt/rustwide/target/debug/deps/libfutures-d1e614fd38b3d8ab.rmeta --cap-lints=warn --crate-version 0.5.0-beta.4` (exit code: 1)
[INFO] running `Command { std: "docker" "inspect" "df8a2b478b051b020f457280f148b67bc5de31735991b23689d75d6be201037b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "df8a2b478b051b020f457280f148b67bc5de31735991b23689d75d6be201037b", kill_on_drop: false }`
[INFO] [stdout] df8a2b478b051b020f457280f148b67bc5de31735991b23689d75d6be201037b