[INFO] fetching crate meio 0.8.0...
[INFO] testing meio-0.8.0 against 1.47.0 for beta-1.48-1
[INFO] extracting crate meio 0.8.0 into /workspace/builds/worker-9/source
[INFO] validating manifest of crates.io crate meio 0.8.0 on toolchain 1.47.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.47.0" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate meio 0.8.0
[INFO] finished tweaking crates.io crate meio 0.8.0
[INFO] tweaked toml for crates.io crate meio 0.8.0 written to /workspace/builds/worker-9/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.47.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.47.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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" "+1.47.0" "metadata" "--no-deps" "--format-version=1", 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] ba871a6d4797dce99be02c5fd6d3a06cd13b6875fe292f123213b8eaa77587ff
[INFO] running `Command { std: "docker" "start" "-a" "ba871a6d4797dce99be02c5fd6d3a06cd13b6875fe292f123213b8eaa77587ff", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "ba871a6d4797dce99be02c5fd6d3a06cd13b6875fe292f123213b8eaa77587ff", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ba871a6d4797dce99be02c5fd6d3a06cd13b6875fe292f123213b8eaa77587ff", kill_on_drop: false }`
[INFO] [stdout] ba871a6d4797dce99be02c5fd6d3a06cd13b6875fe292f123213b8eaa77587ff
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+1.47.0" "build" "--frozen" "--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] 40e35f42fcbc72907e477d1adaf3e0b936285236678c0673549447d3ea98a795
[INFO] running `Command { std: "docker" "start" "-a" "40e35f42fcbc72907e477d1adaf3e0b936285236678c0673549447d3ea98a795", kill_on_drop: false }`
[INFO] [stderr]    Compiling syn v1.0.44
[INFO] [stderr]    Compiling memchr v2.3.3
[INFO] [stderr]    Compiling pin-project-internal v0.4.27
[INFO] [stderr]    Compiling getrandom v0.1.15
[INFO] [stderr]    Compiling slab v0.4.2
[INFO] [stderr]    Compiling futures-core v0.3.6
[INFO] [stderr]    Compiling proc-macro-nested v0.1.6
[INFO] [stderr]    Compiling once_cell v1.4.1
[INFO] [stderr]    Compiling futures-sink v0.3.6
[INFO] [stderr]    Compiling proc-macro-hack v0.5.18
[INFO] [stderr]    Compiling pin-utils v0.1.0
[INFO] [stderr]    Compiling ppv-lite86 v0.2.9
[INFO] [stderr]    Compiling futures-io v0.3.6
[INFO] [stderr]    Compiling anyhow v1.0.33
[INFO] [stderr]    Compiling arc-swap v0.4.7
[INFO] [stderr]    Compiling pin-project-lite v0.1.10
[INFO] [stderr]    Compiling bytes v0.5.6
[INFO] [stderr]    Compiling fnv v1.0.7
[INFO] [stderr]    Compiling futures-channel v0.3.6
[INFO] [stderr]    Compiling futures-task v0.3.6
[INFO] [stderr]    Compiling iovec v0.1.4
[INFO] [stderr]    Compiling net2 v0.2.35
[INFO] [stderr]    Compiling num_cpus v1.13.0
[INFO] [stderr]    Compiling signal-hook-registry v1.2.1
[INFO] [stderr]    Compiling rand_core v0.5.1
[INFO] [stderr]    Compiling mio v0.6.22
[INFO] [stderr]    Compiling rand_chacha v0.2.2
[INFO] [stderr]    Compiling rand v0.7.3
[INFO] [stderr]    Compiling mio-uds v0.6.8
[INFO] [stderr]    Compiling uuid v0.8.1
[INFO] [stderr]    Compiling futures-macro v0.3.6
[INFO] [stderr]    Compiling tokio-macros v0.2.5
[INFO] [stderr]    Compiling derive_more v0.99.11
[INFO] [stderr]    Compiling async-trait v0.1.41
[INFO] [stderr]    Compiling tokio v0.2.22
[INFO] [stderr]    Compiling pin-project v0.4.27
[INFO] [stderr]    Compiling futures-util v0.3.6
[INFO] [stderr]    Compiling futures-executor v0.3.6
[INFO] [stderr]    Compiling futures v0.3.6
[INFO] [stderr]    Compiling meio v0.8.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> src/lib.rs:13:1
[INFO] [stdout]    |
[INFO] [stdout] 13 | #![feature(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 `meio`.
[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" "40e35f42fcbc72907e477d1adaf3e0b936285236678c0673549447d3ea98a795", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "40e35f42fcbc72907e477d1adaf3e0b936285236678c0673549447d3ea98a795", kill_on_drop: false }`
[INFO] [stdout] 40e35f42fcbc72907e477d1adaf3e0b936285236678c0673549447d3ea98a795
