[INFO] fetching crate alloc-cortex-m 0.4.1...
[INFO] testing alloc-cortex-m-0.4.1 against 1.49.0 for beta-1.50-1
[INFO] extracting crate alloc-cortex-m 0.4.1 into /workspace/builds/worker-7/source
[INFO] validating manifest of crates.io crate alloc-cortex-m 0.4.1 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 alloc-cortex-m 0.4.1
[INFO] finished tweaking crates.io crate alloc-cortex-m 0.4.1
[INFO] tweaked toml for crates.io crate alloc-cortex-m 0.4.1 written to /workspace/builds/worker-7/source/Cargo.toml
[INFO] crate crates.io crate alloc-cortex-m 0.4.1 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-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/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] 044470b72f7b2547a926b0b6c387eed735b29f412c8812e39c4b824fb0891bc9
[INFO] running `Command { std: "docker" "start" "-a" "044470b72f7b2547a926b0b6c387eed735b29f412c8812e39c4b824fb0891bc9", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "044470b72f7b2547a926b0b6c387eed735b29f412c8812e39c4b824fb0891bc9", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "044470b72f7b2547a926b0b6c387eed735b29f412c8812e39c4b824fb0891bc9", kill_on_drop: false }`
[INFO] [stdout] 044470b72f7b2547a926b0b6c387eed735b29f412c8812e39c4b824fb0891bc9
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 4b42f84a66db6c0035620f11cad8809f6f233cc35e94bf25c0759356624e2190
[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" "4b42f84a66db6c0035620f11cad8809f6f233cc35e94bf25c0759356624e2190", kill_on_drop: false }`
[INFO] [stderr]    Compiling stable_deref_trait v1.2.0
[INFO] [stderr]    Compiling vcell v0.1.3
[INFO] [stderr]    Compiling bitfield v0.13.2
[INFO] [stderr]    Compiling linked_list_allocator v0.8.11
[INFO] [stderr]    Compiling generic-array v0.14.4
[INFO] [stderr]    Compiling generic-array v0.13.2
[INFO] [stderr]    Compiling generic-array v0.12.3
[INFO] [stderr]    Compiling bare-metal v0.2.5
[INFO] [stderr]    Compiling volatile-register v0.2.0
[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/linked_list_allocator-0.8.11/src/lib.rs:1:41
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![cfg_attr(feature = "const_mut_refs", feature(const_mut_refs))]
[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 `linked_list_allocator`
[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" "4b42f84a66db6c0035620f11cad8809f6f233cc35e94bf25c0759356624e2190", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "4b42f84a66db6c0035620f11cad8809f6f233cc35e94bf25c0759356624e2190", kill_on_drop: false }`
[INFO] [stdout] 4b42f84a66db6c0035620f11cad8809f6f233cc35e94bf25c0759356624e2190