[INFO] fetching crate agilulf_skiplist 0.1.0...
[INFO] testing agilulf_skiplist-0.1.0 against 1.60.0 for beta-1.61-1
[INFO] extracting crate agilulf_skiplist 0.1.0 into /workspace/builds/worker-28/source
[INFO] validating manifest of crates.io crate agilulf_skiplist 0.1.0 on toolchain 1.60.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.60.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate agilulf_skiplist 0.1.0
[INFO] finished tweaking crates.io crate agilulf_skiplist 0.1.0
[INFO] tweaked toml for crates.io crate agilulf_skiplist 0.1.0 written to /workspace/builds/worker-28/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.60.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.60.0" "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 futures-executor-preview v0.3.0-alpha.17
[INFO] [stderr]   Downloaded futures-channel-preview v0.3.0-alpha.17
[INFO] [stderr]   Downloaded futures-core-preview v0.3.0-alpha.17
[INFO] [stderr]   Downloaded futures-sink-preview v0.3.0-alpha.17
[INFO] [stderr]   Downloaded agilulf_protocol v0.1.0
[INFO] [stderr]   Downloaded futures-io-preview v0.3.0-alpha.17
[INFO] [stderr]   Downloaded futures-select-macro-preview v0.3.0-alpha.17
[INFO] [stderr]   Downloaded futures-preview v0.3.0-alpha.17
[INFO] [stderr]   Downloaded romio v0.3.0-alpha.9
[INFO] [stderr]   Downloaded futures-util-preview v0.3.0-alpha.17
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-28/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-28/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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+1.60.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] b2f99330904ef0b7da5ff12f3acc5b312b9fefc91ab758507adea2f0ac582c40
[INFO] running `Command { std: "docker" "start" "-a" "b2f99330904ef0b7da5ff12f3acc5b312b9fefc91ab758507adea2f0ac582c40", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "b2f99330904ef0b7da5ff12f3acc5b312b9fefc91ab758507adea2f0ac582c40", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b2f99330904ef0b7da5ff12f3acc5b312b9fefc91ab758507adea2f0ac582c40", kill_on_drop: false }`
[INFO] [stdout] b2f99330904ef0b7da5ff12f3acc5b312b9fefc91ab758507adea2f0ac582c40
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-28/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-28/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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+1.60.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 166149501e613ce15bbe551b7f7fa9948d2132f09406dfc15608b9b6cc73052a
[INFO] running `Command { std: "docker" "start" "-a" "166149501e613ce15bbe551b7f7fa9948d2132f09406dfc15608b9b6cc73052a", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v0.4.30
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling futures-core-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling stable_deref_trait v1.2.0
[INFO] [stderr]    Compiling futures-io-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling scopeguard v0.3.3
[INFO] [stderr]    Compiling async-ready v3.0.0
[INFO] [stderr]    Compiling async-datagram v3.0.0
[INFO] [stderr]    Compiling semver v0.9.0
[INFO] [stderr]    Compiling iovec v0.1.4
[INFO] [stderr]    Compiling net2 v0.2.37
[INFO] [stderr]    Compiling rand v0.7.3
[INFO] [stderr]    Compiling owning_ref v0.4.1
[INFO] [stderr]    Compiling futures-sink-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling rustc_version v0.2.3
[INFO] [stderr]    Compiling lock_api v0.1.5
[INFO] [stderr]    Compiling mio v0.6.23
[INFO] [stderr]    Compiling futures-channel-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling parking_lot_core v0.4.0
[INFO] [stderr]    Compiling quote v0.6.13
[INFO] [stderr]    Compiling mio-uds v0.6.8
[INFO] [stderr]    Compiling parking_lot v0.7.1
[INFO] [stderr]    Compiling futures-select-macro-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling futures-util-preview v0.3.0-alpha.17
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/futures-util-preview-0.3.0-alpha.17/src/lib.rs:4:38
[INFO] [stdout]   |
[INFO] [stdout] 4 | #![cfg_attr(feature = "async-await", feature(async_await))]
[INFO] [stdout]   |                                      ^^^^^^^^^^^^^^^^^^^^ help: remove the attribute
[INFO] [stdout]   |
[INFO] [stdout]   = help: the feature `async_await` has been stable since 1.39.0 and no longer requires an attribute to enable
[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-util-preview` due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "166149501e613ce15bbe551b7f7fa9948d2132f09406dfc15608b9b6cc73052a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "166149501e613ce15bbe551b7f7fa9948d2132f09406dfc15608b9b6cc73052a", kill_on_drop: false }`
[INFO] [stdout] 166149501e613ce15bbe551b7f7fa9948d2132f09406dfc15608b9b6cc73052a