[INFO] fetching crate aktoro-runtime 0.1.0-alpha.4...
[INFO] testing aktoro-runtime-0.1.0-alpha.4 against 1.49.0 for beta-1.50-1
[INFO] extracting crate aktoro-runtime 0.1.0-alpha.4 into /workspace/builds/worker-5/source
[INFO] validating manifest of crates.io crate aktoro-runtime 0.1.0-alpha.4 on toolchain 1.49.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate aktoro-runtime 0.1.0-alpha.4
[INFO] finished tweaking crates.io crate aktoro-runtime 0.1.0-alpha.4
[INFO] tweaked toml for crates.io crate aktoro-runtime 0.1.0-alpha.4 written to /workspace/builds/worker-5/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "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" "+1.49.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[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:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 49f8cfa6f0922d161a040219759526590467a09ee1898ab68d548c344f624431
[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" "49f8cfa6f0922d161a040219759526590467a09ee1898ab68d548c344f624431", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "49f8cfa6f0922d161a040219759526590467a09ee1898ab68d548c344f624431", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "49f8cfa6f0922d161a040219759526590467a09ee1898ab68d548c344f624431", kill_on_drop: false }`
[INFO] [stdout] 49f8cfa6f0922d161a040219759526590467a09ee1898ab68d548c344f624431
[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" "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" "rustops/crates-build-env@sha256:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] e569fd8841804ec3ae9c5b0c884f147e24107b84dbe6a00bd9f6344041cee794
[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" "e569fd8841804ec3ae9c5b0c884f147e24107b84dbe6a00bd9f6344041cee794", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.24
[INFO] [stderr]    Compiling futures-core-preview v0.3.0-alpha.19
[INFO] [stderr]    Compiling futures-io-preview v0.3.0-alpha.19
[INFO] [stderr]    Compiling futures-sink-preview v0.3.0-alpha.19
[INFO] [stderr]    Compiling pin-project-internal v0.4.27
[INFO] [stderr]    Compiling crossbeam-utils v0.6.6
[INFO] [stderr]    Compiling rand_os v0.1.3
[INFO] [stderr]    Compiling rand_xoshiro v0.2.0
[INFO] [stderr]    Compiling futures-channel-preview v0.3.0-alpha.19
[INFO] [stderr]    Compiling rand v0.6.5
[INFO] [stderr]    Compiling crossbeam-queue v0.1.2
[INFO] [stderr]    Compiling aktoro-raw v0.1.0-alpha.4
[INFO] [stderr]    Compiling futures-util-preview v0.3.0-alpha.19
[INFO] [stderr]    Compiling aktoro-channel v0.1.0-alpha.8
[INFO] [stderr]    Compiling quote v1.0.8
[INFO] [stderr]    Compiling syn v1.0.57
[INFO] [stderr]    Compiling futures-executor-preview v0.3.0-alpha.19
[INFO] [stderr]    Compiling futures-preview v0.3.0-alpha.19
[INFO] [stderr]    Compiling runtime-raw v0.3.0-alpha.5
[INFO] [stderr]    Compiling runtime-attributes v0.3.0-alpha.6
[INFO] [stderr]    Compiling pin-project v0.4.27
[INFO] [stderr]    Compiling runtime v0.3.0-alpha.8
[INFO] [stderr]    Compiling aktoro-runtime v0.1.0-alpha.4 (/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_await)]
[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 `aktoro-runtime`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "e569fd8841804ec3ae9c5b0c884f147e24107b84dbe6a00bd9f6344041cee794", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e569fd8841804ec3ae9c5b0c884f147e24107b84dbe6a00bd9f6344041cee794", kill_on_drop: false }`
[INFO] [stdout] e569fd8841804ec3ae9c5b0c884f147e24107b84dbe6a00bd9f6344041cee794