[INFO] fetching crate mango 0.4.0...
[INFO] documenting mango-0.4.0 against 1.46.0 for beta-1.47-rustdoc-1
[INFO] extracting crate mango 0.4.0 into /workspace/builds/worker-12/source
[INFO] validating manifest of crates.io crate mango 0.4.0 on toolchain 1.46.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.46.0" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate mango 0.4.0
[INFO] finished tweaking crates.io crate mango 0.4.0
[INFO] tweaked toml for crates.io crate mango 0.4.0 written to /workspace/builds/worker-12/source/Cargo.toml
[INFO] crate crates.io crate mango 0.4.0 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.46.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/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" "+1.46.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 5a0d17ddcc87c9e30f36b97c11a687932a072adbbbf19036583a196e11591999
[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" "5a0d17ddcc87c9e30f36b97c11a687932a072adbbbf19036583a196e11591999", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "5a0d17ddcc87c9e30f36b97c11a687932a072adbbbf19036583a196e11591999", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5a0d17ddcc87c9e30f36b97c11a687932a072adbbbf19036583a196e11591999", kill_on_drop: false }`
[INFO] [stdout] 5a0d17ddcc87c9e30f36b97c11a687932a072adbbbf19036583a196e11591999
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/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" "+1.46.0" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 3055c55c0ec0ab9ca69d02002fe3649a16ba2dc7487319f4942cbedc5351a1b4
[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" "3055c55c0ec0ab9ca69d02002fe3649a16ba2dc7487319f4942cbedc5351a1b4", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.18
[INFO] [stderr]    Compiling memchr v2.3.3
[INFO] [stderr]    Compiling unicode-xid v0.2.0
[INFO] [stderr]    Compiling maybe-uninit v2.0.0
[INFO] [stderr]    Compiling serde v1.0.111
[INFO] [stderr]    Compiling syn v1.0.31
[INFO] [stderr]     Checking lazy_static v1.4.0
[INFO] [stderr]     Checking either v1.5.3
[INFO] [stderr]     Checking regex-syntax v0.6.18
[INFO] [stderr]     Checking parity-wasm v0.41.0
[INFO] [stderr]     Checking thread_local v1.0.1
[INFO] [stderr]     Checking itertools v0.8.2
[INFO] [stderr]     Checking smallvec v0.6.13
[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/smallvec-0.6.13/lib.rs:32:32
[INFO] [stdout]    |
[INFO] [stdout] 32 | #![cfg_attr(feature = "union", feature(untagged_unions))]
[INFO] [stdout]    |                                ^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Checking aho-corasick v0.7.10
[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 `smallvec`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "3055c55c0ec0ab9ca69d02002fe3649a16ba2dc7487319f4942cbedc5351a1b4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "3055c55c0ec0ab9ca69d02002fe3649a16ba2dc7487319f4942cbedc5351a1b4", kill_on_drop: false }`
[INFO] [stdout] 3055c55c0ec0ab9ca69d02002fe3649a16ba2dc7487319f4942cbedc5351a1b4