[INFO] cloning repository https://github.com/brinchj/rust-sudoku-fun
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/brinchj/rust-sudoku-fun" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbrinchj%2Frust-sudoku-fun", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbrinchj%2Frust-sudoku-fun'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 849f6a4ac8d2168e7a273a5b1bbee70e6837cb2d
[INFO] documenting brinchj/rust-sudoku-fun against 1.46.0 for beta-1.47-rustdoc-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbrinchj%2Frust-sudoku-fun" "/workspace/builds/worker-13/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-13/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/brinchj/rust-sudoku-fun 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 git repo https://github.com/brinchj/rust-sudoku-fun
[INFO] finished tweaking git repo https://github.com/brinchj/rust-sudoku-fun
[INFO] tweaked toml for git repo https://github.com/brinchj/rust-sudoku-fun written to /workspace/builds/worker-13/source/Cargo.toml
[INFO] crate git repo https://github.com/brinchj/rust-sudoku-fun 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] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/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] 7430d329acf9429aa022a2ac7e9973c938d77dd4261559a94c1dfa5b669e7e01
[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" "7430d329acf9429aa022a2ac7e9973c938d77dd4261559a94c1dfa5b669e7e01", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "7430d329acf9429aa022a2ac7e9973c938d77dd4261559a94c1dfa5b669e7e01", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7430d329acf9429aa022a2ac7e9973c938d77dd4261559a94c1dfa5b669e7e01", kill_on_drop: false }`
[INFO] [stdout] 7430d329acf9429aa022a2ac7e9973c938d77dd4261559a94c1dfa5b669e7e01
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/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] 5d695af59ee1c088a6665150dcdaa9de90f27bdfa879ab965e1a846a8414dd38
[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" "5d695af59ee1c088a6665150dcdaa9de90f27bdfa879ab965e1a846a8414dd38", kill_on_drop: false }`
[INFO] [stderr]    Compiling debugtrace v0.1.0
[INFO] [stderr]     Checking debug-builders v0.1.0
[INFO] [stderr]     Checking either v0.1.7
[INFO] [stderr]     Checking conv v0.3.3
[INFO] [stderr]    Compiling rustc_version v0.2.2
[INFO] [stderr]    Compiling backtrace-sys v0.1.23
[INFO] [stderr]    Compiling im v10.2.0
[INFO] [stderr]     Checking backtrace v0.1.8
[INFO] [stderr]     Checking backtrace v0.3.8
[INFO] [stderr]     Checking failure v0.1.1
[INFO] [stderr]     Checking chomp v0.3.1
[INFO] [stderr]  Documenting sudokusolver v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(iterator_step_by)]
[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 `sudokusolver`.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --crate-type lib --crate-name sudokusolver 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 chomp=/opt/rustwide/target/debug/deps/libchomp-f7294b37e880f358.rmeta --extern failure=/opt/rustwide/target/debug/deps/libfailure-eeeb77d0d114754e.rmeta --extern im=/opt/rustwide/target/debug/deps/libim-4ef23f43009bf3c5.rmeta --cap-lints=warn` (exit code: 1)
[INFO] running `Command { std: "docker" "inspect" "5d695af59ee1c088a6665150dcdaa9de90f27bdfa879ab965e1a846a8414dd38", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5d695af59ee1c088a6665150dcdaa9de90f27bdfa879ab965e1a846a8414dd38", kill_on_drop: false }`
[INFO] [stdout] 5d695af59ee1c088a6665150dcdaa9de90f27bdfa879ab965e1a846a8414dd38