[INFO] cloning repository https://github.com/chmln/fut-err
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/chmln/fut-err" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fchmln%2Ffut-err", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fchmln%2Ffut-err'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 97947046d157aa1c901118c1f25848dbb4d50ed5
[INFO] documenting chmln/fut-err against beta-2020-08-29 for beta-1.47-rustdoc-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fchmln%2Ffut-err" "/workspace/builds/worker-3/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/chmln/fut-err 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 git repo https://github.com/chmln/fut-err
[INFO] finished tweaking git repo https://github.com/chmln/fut-err
[INFO] tweaked toml for git repo https://github.com/chmln/fut-err written to /workspace/builds/worker-3/source/Cargo.toml
[INFO] crate git repo https://github.com/chmln/fut-err 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] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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] b134c38ee13bc2a325dac1ce551beaba8599a73fb7a46c1abd141b3aa84d8c43
[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" "b134c38ee13bc2a325dac1ce551beaba8599a73fb7a46c1abd141b3aa84d8c43", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "b134c38ee13bc2a325dac1ce551beaba8599a73fb7a46c1abd141b3aa84d8c43", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b134c38ee13bc2a325dac1ce551beaba8599a73fb7a46c1abd141b3aa84d8c43", kill_on_drop: false }`
[INFO] [stdout] b134c38ee13bc2a325dac1ce551beaba8599a73fb7a46c1abd141b3aa84d8c43
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 6d9b7809a6ca24498ab84619cba3a5c435c31ab44f5a208df88f8e14d1f0d5cb
[INFO] running `Command { std: "docker" "start" "-a" "6d9b7809a6ca24498ab84619cba3a5c435c31ab44f5a208df88f8e14d1f0d5cb", kill_on_drop: false }`
[INFO] [stderr]     Checking either v1.5.2
[INFO] [stderr]    Compiling syn v0.15.32
[INFO] [stderr]     Checking rand_core v0.3.1
[INFO] [stderr]     Checking rand_chacha v0.1.1
[INFO] [stderr]     Checking rand_isaac v0.1.1
[INFO] [stderr]     Checking rand_hc v0.1.0
[INFO] [stderr]     Checking rand_xorshift v0.1.1
[INFO] [stderr]     Checking futures-core-preview v0.3.0-alpha.14
[INFO] [stderr]     Checking rand v0.6.5
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/futures-core-preview-0.3.0-alpha.14/src/lib.rs:3:1
[INFO] [stdout]   |
[INFO] [stdout] 3 | #![feature(futures_api)]
[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 E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `futures-core-preview`.
[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" "6d9b7809a6ca24498ab84619cba3a5c435c31ab44f5a208df88f8e14d1f0d5cb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6d9b7809a6ca24498ab84619cba3a5c435c31ab44f5a208df88f8e14d1f0d5cb", kill_on_drop: false }`
[INFO] [stdout] 6d9b7809a6ca24498ab84619cba3a5c435c31ab44f5a208df88f8e14d1f0d5cb