[INFO] fetching crate rug-maths 0.2.5...
[INFO] testing rug-maths-0.2.5 against 1.55.0 for beta-1.56-1
[INFO] extracting crate rug-maths 0.2.5 into /workspace/builds/worker-39/source
[INFO] validating manifest of crates.io crate rug-maths 0.2.5 on toolchain 1.55.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate rug-maths 0.2.5
[INFO] finished tweaking crates.io crate rug-maths 0.2.5
[INFO] tweaked toml for crates.io crate rug-maths 0.2.5 written to /workspace/builds/worker-39/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded az v1.1.2
[INFO] [stderr]   Downloaded maths-traits v0.2.1
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-39/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-39/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] b16b67b6dcf8a6dc5c6ead13a124889dccbdccace0a0f466abc1568a7c75476b
[INFO] running `Command { std: "docker" "start" "-a" "b16b67b6dcf8a6dc5c6ead13a124889dccbdccace0a0f466abc1568a7c75476b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "b16b67b6dcf8a6dc5c6ead13a124889dccbdccace0a0f466abc1568a7c75476b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b16b67b6dcf8a6dc5c6ead13a124889dccbdccace0a0f466abc1568a7c75476b", kill_on_drop: false }`
[INFO] [stdout] b16b67b6dcf8a6dc5c6ead13a124889dccbdccace0a0f466abc1568a7c75476b
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-39/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-39/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 994ec408b9c4407b11047dded8b26edd0c9d131adaac60cee641dc72a671aab0
[INFO] running `Command { std: "docker" "start" "-a" "994ec408b9c4407b11047dded8b26edd0c9d131adaac60cee641dc72a671aab0", kill_on_drop: false }`
[INFO] [stderr]    Compiling gmp-mpfr-sys v1.4.6
[INFO] [stderr]    Compiling libc v0.2.101
[INFO] [stderr]    Compiling az v1.1.2
[INFO] [stderr]    Compiling rug v1.13.0
[INFO] [stderr]    Compiling maths-traits v0.2.1
[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/maths-traits-0.2.1/src/lib.rs:317:1
[INFO] [stdout]     |
[INFO] [stdout] 317 | #![feature(trait_alias)]
[INFO] [stdout]     | ^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[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/maths-traits-0.2.1/src/lib.rs:318:1
[INFO] [stdout]     |
[INFO] [stdout] 318 | #![feature(specialization)]
[INFO] [stdout]     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[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/maths-traits-0.2.1/src/lib.rs:319:1
[INFO] [stdout]     |
[INFO] [stdout] 319 | #![feature(extra_log_consts)]
[INFO] [stdout]     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 3 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `maths-traits` due to 4 previous errors
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "994ec408b9c4407b11047dded8b26edd0c9d131adaac60cee641dc72a671aab0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "994ec408b9c4407b11047dded8b26edd0c9d131adaac60cee641dc72a671aab0", kill_on_drop: false }`
[INFO] [stdout] 994ec408b9c4407b11047dded8b26edd0c9d131adaac60cee641dc72a671aab0