[INFO] cloning repository https://github.com/iyuroch/rust_word_counter
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/iyuroch/rust_word_counter" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fiyuroch%2Frust_word_counter", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fiyuroch%2Frust_word_counter'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 12ee883c7ff016ca88ac16f4d8e9fc7a7682612c
[INFO] testing iyuroch/rust_word_counter against 1.49.0 for beta-1.50-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fiyuroch%2Frust_word_counter" "/workspace/builds/worker-4/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/iyuroch/rust_word_counter 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 git repo https://github.com/iyuroch/rust_word_counter
[INFO] finished tweaking git repo https://github.com/iyuroch/rust_word_counter
[INFO] tweaked toml for git repo https://github.com/iyuroch/rust_word_counter written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] crate git repo https://github.com/iyuroch/rust_word_counter already has a lockfile, it will not be regenerated
[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-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] d904352069fa11e9e005ebca1790159400e355b64b95b361c0f3894c0f56722a
[INFO] running `Command { std: "docker" "start" "-a" "d904352069fa11e9e005ebca1790159400e355b64b95b361c0f3894c0f56722a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "d904352069fa11e9e005ebca1790159400e355b64b95b361c0f3894c0f56722a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d904352069fa11e9e005ebca1790159400e355b64b95b361c0f3894c0f56722a", kill_on_drop: false }`
[INFO] [stdout] d904352069fa11e9e005ebca1790159400e355b64b95b361c0f3894c0f56722a
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 39b9e8914778b53bfedd50e4a5b774e7d572e0798e8cda879f4ecbdb0029c96a
[INFO] running `Command { std: "docker" "start" "-a" "39b9e8914778b53bfedd50e4a5b774e7d572e0798e8cda879f4ecbdb0029c96a", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.42
[INFO] [stderr]    Compiling cfg-if v0.1.3
[INFO] [stderr]    Compiling nodrop v0.1.12
[INFO] [stderr]    Compiling lazy_static v1.0.1
[INFO] [stderr]    Compiling rayon-core v1.4.0
[INFO] [stderr]    Compiling serde v1.0.66
[INFO] [stderr]    Compiling stable_deref_trait v1.1.0
[INFO] [stderr]    Compiling smallvec v0.6.2
[INFO] [stderr]    Compiling rand_core v0.2.1
[INFO] [stderr]    Compiling crossbeam-utils v0.4.1
[INFO] [stderr]    Compiling either v1.5.0
[INFO] [stderr]    Compiling itoa v0.4.1
[INFO] [stderr]    Compiling dtoa v0.4.2
[INFO] [stderr]    Compiling spmc v0.2.2
[INFO] [stderr]    Compiling crossbeam v0.3.2
[INFO] [stderr]    Compiling canal v0.1.3
[INFO] [stderr]    Compiling proc-macro2 v0.4.6
[INFO] [stderr]    Compiling arrayvec v0.4.7
[INFO] [stderr]    Compiling crossbeam-utils v0.2.2
[INFO] [stderr]    Compiling owning_ref v0.3.3
[INFO] [stderr]    Compiling crossbeam-epoch v0.3.1
[INFO] [stderr]    Compiling crossbeam-epoch v0.5.0
[INFO] [stderr]    Compiling quote v0.6.3
[INFO] [stderr]    Compiling rand v0.4.2
[INFO] [stderr]    Compiling num_cpus v1.8.0
[INFO] [stderr]    Compiling rand v0.5.4
[INFO] [stderr]    Compiling syn v0.14.2
[INFO] [stderr]    Compiling crossbeam-deque v0.2.0
[INFO] [stderr]    Compiling parking_lot_core v0.2.14
[INFO] [stderr]    Compiling rand v0.3.22
[INFO] [stderr]    Compiling chan v0.1.21
[INFO] [stderr]    Compiling parking_lot v0.5.5
[INFO] [stderr]    Compiling rayon v1.0.1
[INFO] [stderr]    Compiling crossbeam-channel v0.2.2
[INFO] [stderr]    Compiling serde_derive v1.0.66
[INFO] [stderr]    Compiling serde_json v1.0.20
[INFO] [stderr]    Compiling word_counter v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/main.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(io)]
[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 `word_counter`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "39b9e8914778b53bfedd50e4a5b774e7d572e0798e8cda879f4ecbdb0029c96a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "39b9e8914778b53bfedd50e4a5b774e7d572e0798e8cda879f4ecbdb0029c96a", kill_on_drop: false }`
[INFO] [stdout] 39b9e8914778b53bfedd50e4a5b774e7d572e0798e8cda879f4ecbdb0029c96a