[INFO] fetching crate mcio 0.3.1...
[INFO] documenting mcio-0.3.1 against beta-2020-08-29 for beta-1.47-rustdoc-1
[INFO] extracting crate mcio 0.3.1 into /workspace/builds/worker-1/source
[INFO] validating manifest of crates.io crate mcio 0.3.1 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 mcio 0.3.1
[INFO] finished tweaking crates.io crate mcio 0.3.1
[INFO] tweaked toml for crates.io crate mcio 0.3.1 written to /workspace/builds/worker-1/source/Cargo.toml
[INFO] crate crates.io crate mcio 0.3.1 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]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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] 38be39a3b0e0fdb20ed26aed25f80a950b7e985fbfcb8e81533919617af92bf8
[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" "38be39a3b0e0fdb20ed26aed25f80a950b7e985fbfcb8e81533919617af92bf8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "38be39a3b0e0fdb20ed26aed25f80a950b7e985fbfcb8e81533919617af92bf8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "38be39a3b0e0fdb20ed26aed25f80a950b7e985fbfcb8e81533919617af92bf8", kill_on_drop: false }`
[INFO] [stdout] 38be39a3b0e0fdb20ed26aed25f80a950b7e985fbfcb8e81533919617af92bf8
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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] 29bd7b9bb0063850a29656be0f90ea7af96f662ccf26a1239b94c0e3b186e30b
[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" "29bd7b9bb0063850a29656be0f90ea7af96f662ccf26a1239b94c0e3b186e30b", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Checking smallvec v1.3.0
[INFO] [stderr]     Checking tokio-sync v0.1.8
[INFO] [stderr]    Compiling backtrace-sys v0.1.35
[INFO] [stderr]     Checking iovec v0.1.4
[INFO] [stderr]     Checking num_cpus v1.13.0
[INFO] [stderr]     Checking net2 v0.2.33
[INFO] [stderr]     Checking socket2 v0.3.12
[INFO] [stderr]     Checking rand v0.4.6
[INFO] [stderr]     Checking hostname v0.3.1
[INFO] [stderr]     Checking parking_lot_core v0.6.2
[INFO] [stderr]     Checking serde_json v1.0.51
[INFO] [stderr]     Checking resolv-conf v0.6.3
[INFO] [stderr]     Checking bytes v0.4.12
[INFO] [stderr]     Checking tokio-threadpool v0.1.18
[INFO] [stderr]     Checking unicode-normalization v0.1.12
[INFO] [stderr]     Checking parking_lot v0.9.0
[INFO] [stderr]     Checking mio v0.6.21
[INFO] [stderr]     Checking tokio-io v0.1.13
[INFO] [stderr]     Checking mio-uds v0.6.7
[INFO] [stderr]     Checking tokio-reactor v0.1.12
[INFO] [stderr]     Checking tokio-codec v0.1.2
[INFO] [stderr]     Checking tokio-fs v0.1.7
[INFO] [stderr]     Checking backtrace v0.2.3
[INFO] [stderr]     Checking idna v0.1.5
[INFO] [stderr]     Checking error-chain v0.1.12
[INFO] [stderr]     Checking tokio-udp v0.1.6
[INFO] [stderr]     Checking tokio-tcp v0.1.4
[INFO] [stderr]     Checking tokio-uds v0.2.6
[INFO] [stderr]     Checking tokio v0.1.22
[INFO] [stderr]     Checking url v1.7.2
[INFO] [stderr]     Checking trust-dns-proto v0.4.3
[INFO] [stderr]     Checking trust-dns-resolver v0.9.1
[INFO] [stderr]  Documenting mcio v0.3.1 (/opt/rustwide/workdir)
[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(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 `mcio`.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type lib --crate-name mcio 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 serde=/opt/rustwide/target/debug/deps/libserde-2ae9cd59edec41aa.rmeta --extern serde_json=/opt/rustwide/target/debug/deps/libserde_json-27f3229cf447c600.rmeta --extern trust_dns_resolver=/opt/rustwide/target/debug/deps/libtrust_dns_resolver-74df8b6674651616.rmeta --cap-lints=warn --crate-version 0.3.1` (exit code: 1)
[INFO] running `Command { std: "docker" "inspect" "29bd7b9bb0063850a29656be0f90ea7af96f662ccf26a1239b94c0e3b186e30b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "29bd7b9bb0063850a29656be0f90ea7af96f662ccf26a1239b94c0e3b186e30b", kill_on_drop: false }`
[INFO] [stdout] 29bd7b9bb0063850a29656be0f90ea7af96f662ccf26a1239b94c0e3b186e30b