[INFO] updating cached repository https://github.com/benaryorg/rust-loop_benchmarking
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "-c" "remote.origin.fetch=refs/heads/*:refs/heads/*" "fetch" "origin" "--force" "--prune", kill_on_drop: false }`
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 80cf66c5aa1e00a647c0b89f82efed88bfac73e3
[INFO] documenting benaryorg/rust-loop_benchmarking against master#394e1b40d264aa6928811919c1124fa248e7d802 for pr-73566
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbenaryorg%2Frust-loop_benchmarking" "/workspace/builds/worker-6/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-6/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/benaryorg/rust-loop_benchmarking on toolchain 394e1b40d264aa6928811919c1124fa248e7d802
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+394e1b40d264aa6928811919c1124fa248e7d802" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/benaryorg/rust-loop_benchmarking
[INFO] finished tweaking git repo https://github.com/benaryorg/rust-loop_benchmarking
[INFO] tweaked toml for git repo https://github.com/benaryorg/rust-loop_benchmarking written to /workspace/builds/worker-6/source/Cargo.toml
[INFO] crate git repo https://github.com/benaryorg/rust-loop_benchmarking already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+394e1b40d264aa6928811919c1124fa248e7d802" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:819119df93c0f5eca3f29186f14981ef29945a311854d7222af07488600a2584" "/opt/rustwide/cargo-home/bin/cargo" "+394e1b40d264aa6928811919c1124fa248e7d802" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 5263170bcc05a47694a04f3cfd245fb0e91f46f7ef872b07c4e194770b958ef4
[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" "5263170bcc05a47694a04f3cfd245fb0e91f46f7ef872b07c4e194770b958ef4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "5263170bcc05a47694a04f3cfd245fb0e91f46f7ef872b07c4e194770b958ef4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5263170bcc05a47694a04f3cfd245fb0e91f46f7ef872b07c4e194770b958ef4", kill_on_drop: false }`
[INFO] [stdout] 5263170bcc05a47694a04f3cfd245fb0e91f46f7ef872b07c4e194770b958ef4
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/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" "MAP_USER_ID=0" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTDOCFLAGS=--cap-lints=forbid" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--network" "none" "rustops/crates-build-env@sha256:819119df93c0f5eca3f29186f14981ef29945a311854d7222af07488600a2584" "/opt/rustwide/cargo-home/bin/cargo" "+394e1b40d264aa6928811919c1124fa248e7d802" "doc" "--frozen" "--no-deps" "--document-private-items" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] d8bdd7e69f9548b252bc9d87771bd2b02068f4161c3d5ea1e8f00ca66732aa54
[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" "d8bdd7e69f9548b252bc9d87771bd2b02068f4161c3d5ea1e8f00ca66732aa54", kill_on_drop: false }`
[INFO] [stderr]  Documenting loop v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0635]: unknown feature `step_by`
[INFO] [stdout]  --> src/main.rs:2:12
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(step_by)]
[INFO] [stdout]   |            ^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0635`.
[INFO] [stdout] 
[INFO] [stderr] error: Could not document `loop`.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustdoc --crate-type bin --crate-name loop src/main.rs -o /opt/rustwide/target/doc --error-format=json --json=diagnostic-rendered-ansi --document-private-items -L dependency=/opt/rustwide/target/debug/deps --cap-lints=forbid` (exit code: 1)
[INFO] running `Command { std: "docker" "inspect" "d8bdd7e69f9548b252bc9d87771bd2b02068f4161c3d5ea1e8f00ca66732aa54", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d8bdd7e69f9548b252bc9d87771bd2b02068f4161c3d5ea1e8f00ca66732aa54", kill_on_drop: false }`
[INFO] [stdout] d8bdd7e69f9548b252bc9d87771bd2b02068f4161c3d5ea1e8f00ca66732aa54