[INFO] cloning repository https://github.com/swfsql/structopt-external-doc
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/swfsql/structopt-external-doc" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fswfsql%2Fstructopt-external-doc", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fswfsql%2Fstructopt-external-doc'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 9953bdc159513170d9230f8e0d6f691804e95f3b
[INFO] documenting swfsql/structopt-external-doc 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%2Fswfsql%2Fstructopt-external-doc" "/workspace/builds/worker-5/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-5/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/swfsql/structopt-external-doc 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/swfsql/structopt-external-doc
[INFO] finished tweaking git repo https://github.com/swfsql/structopt-external-doc
[INFO] tweaked toml for git repo https://github.com/swfsql/structopt-external-doc written to /workspace/builds/worker-5/source/Cargo.toml
[INFO] crate git repo https://github.com/swfsql/structopt-external-doc 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-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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] 8483fbb8bc81eb72e986e678a44f58a9e9c1571e65dde815f7c2ef147043fee1
[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" "8483fbb8bc81eb72e986e678a44f58a9e9c1571e65dde815f7c2ef147043fee1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "8483fbb8bc81eb72e986e678a44f58a9e9c1571e65dde815f7c2ef147043fee1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8483fbb8bc81eb72e986e678a44f58a9e9c1571e65dde815f7c2ef147043fee1", kill_on_drop: false }`
[INFO] [stdout] 8483fbb8bc81eb72e986e678a44f58a9e9c1571e65dde815f7c2ef147043fee1
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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] d76973f09fb2d3d3447e29d9c80fd1eb147b8bdc1b0b0bd7dae8d9395ff3f048
[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" "d76973f09fb2d3d3447e29d9c80fd1eb147b8bdc1b0b0bd7dae8d9395ff3f048", kill_on_drop: false }`
[INFO] [stderr]    Compiling syn v1.0.33
[INFO] [stderr]    Compiling libc v0.2.72
[INFO] [stderr]     Checking atty v0.2.14
[INFO] [stderr]     Checking clap v2.33.1
[INFO] [stderr]    Compiling syn-mid v0.5.0
[INFO] [stderr]    Compiling proc-macro-error-attr v1.0.3
[INFO] [stderr]    Compiling proc-macro-error v1.0.3
[INFO] [stderr]    Compiling structopt-derive v0.4.8 (https://github.com/swfsql/structopt?rev=6e400fa#6e400fac)
[INFO] [stderr]     Checking structopt v0.3.15 (https://github.com/swfsql/structopt?rev=6e400fa#6e400fac)
[INFO] [stderr]  Documenting structopt-external-doc v0.1.0 (/opt/rustwide/workdir)
[INFO] [stderr] error: Could not document `structopt-external-doc`.
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/main.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(external_doc)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] 
[INFO] [stdout] error: Compilation failed, aborting rustdoc
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] Caused by:
[INFO] [stdout] error: aborting due to 2 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]   process didn't exit successfully: `rustdoc --edition=2018 --crate-type bin --crate-name structopt_external_doc 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 --extern structopt=/opt/rustwide/target/debug/deps/libstructopt-d87e703a1d1cb565.rmeta --cap-lints=warn` (exit code: 1)
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "d76973f09fb2d3d3447e29d9c80fd1eb147b8bdc1b0b0bd7dae8d9395ff3f048", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d76973f09fb2d3d3447e29d9c80fd1eb147b8bdc1b0b0bd7dae8d9395ff3f048", kill_on_drop: false }`
[INFO] [stdout] d76973f09fb2d3d3447e29d9c80fd1eb147b8bdc1b0b0bd7dae8d9395ff3f048