[INFO] fetching crate futures-async-combinators 0.3.2...
[INFO] testing futures-async-combinators-0.3.2 against 1.55.0 for beta-1.56-1
[INFO] extracting crate futures-async-combinators 0.3.2 into /workspace/builds/worker-30/source
[INFO] validating manifest of crates.io crate futures-async-combinators 0.3.2 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-async-combinators 0.3.2
[INFO] finished tweaking crates.io crate futures-async-combinators 0.3.2
[INFO] tweaked toml for crates.io crate futures-async-combinators 0.3.2 written to /workspace/builds/worker-30/source/Cargo.toml
[INFO] crate crates.io crate futures-async-combinators 0.3.2 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded tinytemplate v1.0.2
[INFO] [stderr]   Downloaded crossbeam-queue v0.1.2
[INFO] [stderr]   Downloaded rayon v1.2.0
[INFO] [stderr]   Downloaded rayon-core v1.6.0
[INFO] [stderr]   Downloaded crossbeam-epoch v0.7.2
[INFO] [stderr]   Downloaded proc-macro2 v1.0.4
[INFO] [stderr]   Downloaded cast v0.2.2
[INFO] [stderr]   Downloaded itertools v0.8.0
[INFO] [stderr]   Downloaded bitflags v1.2.0
[INFO] [stderr]   Downloaded arrayvec v0.4.11
[INFO] [stderr]   Downloaded memoffset v0.5.1
[INFO] [stderr]   Downloaded serde v1.0.101
[INFO] [stderr]   Downloaded num_cpus v1.10.1
[INFO] [stderr]   Downloaded crossbeam-deque v0.7.1
[INFO] [stderr]   Downloaded serde_derive v1.0.101
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-30/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-30/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] 3bb5f843771577faddb1369ad76e4f3ed4955ca36351f329c7365aa9f7b44b38
[INFO] running `Command { std: "docker" "start" "-a" "3bb5f843771577faddb1369ad76e4f3ed4955ca36351f329c7365aa9f7b44b38", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "3bb5f843771577faddb1369ad76e4f3ed4955ca36351f329c7365aa9f7b44b38", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "3bb5f843771577faddb1369ad76e4f3ed4955ca36351f329c7365aa9f7b44b38", kill_on_drop: false }`
[INFO] [stdout] 3bb5f843771577faddb1369ad76e4f3ed4955ca36351f329c7365aa9f7b44b38
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-30/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-30/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] bca338fc944a86c92421948059625ea32f77dc496e64bd3d55e4f8381b34eeb3
[INFO] running `Command { std: "docker" "start" "-a" "bca338fc944a86c92421948059625ea32f77dc496e64bd3d55e4f8381b34eeb3", kill_on_drop: false }`
[INFO] [stderr]    Compiling pin-utils v0.1.0-alpha.4
[INFO] [stderr]    Compiling futures-core-preview v0.3.0-alpha.19
[INFO] [stderr]    Compiling futures-async-combinators v0.3.2 (/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(async_closure, gen_future, generators)]
[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-async-combinators` due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "bca338fc944a86c92421948059625ea32f77dc496e64bd3d55e4f8381b34eeb3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "bca338fc944a86c92421948059625ea32f77dc496e64bd3d55e4f8381b34eeb3", kill_on_drop: false }`
[INFO] [stdout] bca338fc944a86c92421948059625ea32f77dc496e64bd3d55e4f8381b34eeb3