[INFO] fetching crate dumb-exec 0.0.7...
[INFO] testing dumb-exec-0.0.7 against 1.49.0 for beta-1.50-1
[INFO] extracting crate dumb-exec 0.0.7 into /workspace/builds/worker-1/source
[INFO] validating manifest of crates.io crate dumb-exec 0.0.7 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 dumb-exec 0.0.7
[INFO] finished tweaking crates.io crate dumb-exec 0.0.7
[INFO] tweaked toml for crates.io crate dumb-exec 0.0.7 written to /workspace/builds/worker-1/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] 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-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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] a7a38ef1ac5435f27a323bb1e9747ca1c26f7f24d94055c90a80a60a2d44f5ca
[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" "a7a38ef1ac5435f27a323bb1e9747ca1c26f7f24d94055c90a80a60a2d44f5ca", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "a7a38ef1ac5435f27a323bb1e9747ca1c26f7f24d94055c90a80a60a2d44f5ca", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a7a38ef1ac5435f27a323bb1e9747ca1c26f7f24d94055c90a80a60a2d44f5ca", kill_on_drop: false }`
[INFO] [stdout] a7a38ef1ac5435f27a323bb1e9747ca1c26f7f24d94055c90a80a60a2d44f5ca
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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] 6aa6ba94f34363a3f63fd8104c2a195ae30cc3ac08f47ea42e48aa0a24aaff0a
[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" "6aa6ba94f34363a3f63fd8104c2a195ae30cc3ac08f47ea42e48aa0a24aaff0a", kill_on_drop: false }`
[INFO] [stderr]    Compiling futures-core-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling slab v0.4.2
[INFO] [stderr]    Compiling pin-utils v0.1.0
[INFO] [stderr]    Compiling futures-io-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling spin v0.4.10
[INFO] [stderr]    Compiling num_cpus v1.13.0
[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/spin-0.4.10/src/lib.rs:6:35
[INFO] [stdout]   |
[INFO] [stdout] 6 | #![cfg_attr(feature = "const_fn", feature(const_fn))]
[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 `spin`
[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" "6aa6ba94f34363a3f63fd8104c2a195ae30cc3ac08f47ea42e48aa0a24aaff0a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6aa6ba94f34363a3f63fd8104c2a195ae30cc3ac08f47ea42e48aa0a24aaff0a", kill_on_drop: false }`
[INFO] [stdout] 6aa6ba94f34363a3f63fd8104c2a195ae30cc3ac08f47ea42e48aa0a24aaff0a