[INFO] fetching crate futures-concurrency 1.0.0...
[INFO] testing futures-concurrency-1.0.0 against 1.55.0 for beta-1.56-1
[INFO] extracting crate futures-concurrency 1.0.0 into /workspace/builds/worker-18/source
[INFO] validating manifest of crates.io crate futures-concurrency 1.0.0 on toolchain 1.55.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate futures-concurrency 1.0.0
[INFO] finished tweaking crates.io crate futures-concurrency 1.0.0
[INFO] tweaked toml for crates.io crate futures-concurrency 1.0.0 written to /workspace/builds/worker-18/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-18/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-18/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] db3bc44c6ed55a89acc0f4988eff193d5eb654c8c64653453278b0de0dfc8ab3
[INFO] running `Command { std: "docker" "start" "-a" "db3bc44c6ed55a89acc0f4988eff193d5eb654c8c64653453278b0de0dfc8ab3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "db3bc44c6ed55a89acc0f4988eff193d5eb654c8c64653453278b0de0dfc8ab3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "db3bc44c6ed55a89acc0f4988eff193d5eb654c8c64653453278b0de0dfc8ab3", kill_on_drop: false }`
[INFO] [stdout] db3bc44c6ed55a89acc0f4988eff193d5eb654c8c64653453278b0de0dfc8ab3
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-18/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-18/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" "RUSTFLAGS=--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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 0029684a8b0c85b56650159d0c4acfe21849497aa4c4a783f99098538770da06
[INFO] running `Command { std: "docker" "start" "-a" "0029684a8b0c85b56650159d0c4acfe21849497aa4c4a783f99098538770da06", kill_on_drop: false }`
[INFO] [stderr]    Compiling syn v1.0.76
[INFO] [stderr]    Compiling futures-core v0.3.17
[INFO] [stderr]    Compiling pin-project-internal v1.0.8
[INFO] [stderr]    Compiling pin-project v1.0.8
[INFO] [stderr]    Compiling futures-concurrency v1.0.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> src/lib.rs:84:1
[INFO] [stdout]    |
[INFO] [stdout] 84 | #![feature(maybe_uninit_uninit_array)]
[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-concurrency` due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "0029684a8b0c85b56650159d0c4acfe21849497aa4c4a783f99098538770da06", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0029684a8b0c85b56650159d0c4acfe21849497aa4c4a783f99098538770da06", kill_on_drop: false }`
[INFO] [stdout] 0029684a8b0c85b56650159d0c4acfe21849497aa4c4a783f99098538770da06