[INFO] fetching crate embedded-builder 0.1.1...
[INFO] testing embedded-builder-0.1.1 against 1.49.0 for beta-1.50-1
[INFO] extracting crate embedded-builder 0.1.1 into /workspace/builds/worker-4/source
[INFO] validating manifest of crates.io crate embedded-builder 0.1.1 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 embedded-builder 0.1.1
[INFO] finished tweaking crates.io crate embedded-builder 0.1.1
[INFO] tweaked toml for crates.io crate embedded-builder 0.1.1 written to /workspace/builds/worker-4/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-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] [stdout] 8b8bc518bd9b104ddfa9867d7004e75b60bdce4949ccbc685ad895e42ca0c7d6
[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" "8b8bc518bd9b104ddfa9867d7004e75b60bdce4949ccbc685ad895e42ca0c7d6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "8b8bc518bd9b104ddfa9867d7004e75b60bdce4949ccbc685ad895e42ca0c7d6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8b8bc518bd9b104ddfa9867d7004e75b60bdce4949ccbc685ad895e42ca0c7d6", kill_on_drop: false }`
[INFO] [stdout] 8b8bc518bd9b104ddfa9867d7004e75b60bdce4949ccbc685ad895e42ca0c7d6
[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] [stdout] be05121fbf7d5584aa39c522239d748edf24f250b1b9a5063ff248b05ee57a71
[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" "be05121fbf7d5584aa39c522239d748edf24f250b1b9a5063ff248b05ee57a71", kill_on_drop: false }`
[INFO] [stderr]    Compiling embedded-builder v0.1.1 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:4:1
[INFO] [stdout]   |
[INFO] [stdout] 4 | #![feature(used)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:5:1
[INFO] [stdout]   |
[INFO] [stdout] 5 | #![feature(const_fn)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused macro definition
[INFO] [stdout]   --> src/helpers.rs:20:1
[INFO] [stdout]    |
[INFO] [stdout] 20 | / macro_rules! concat {
[INFO] [stdout] 21 | |     ($a: expr, $b: expr) => { $a$b };
[INFO] [stdout] 22 | | }
[INFO] [stdout]    | |_^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_macros)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 previous errors; 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `embedded-builder`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "be05121fbf7d5584aa39c522239d748edf24f250b1b9a5063ff248b05ee57a71", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "be05121fbf7d5584aa39c522239d748edf24f250b1b9a5063ff248b05ee57a71", kill_on_drop: false }`
[INFO] [stdout] be05121fbf7d5584aa39c522239d748edf24f250b1b9a5063ff248b05ee57a71