[INFO] fetching crate loader-rs 0.7.0...
[INFO] testing loader-rs-0.7.0 against 1.55.0 for beta-1.56-1
[INFO] extracting crate loader-rs 0.7.0 into /workspace/builds/worker-6/source
[INFO] validating manifest of crates.io crate loader-rs 0.7.0 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] removed /workspace/builds/worker-6/source/rust-toolchain
[INFO] started tweaking crates.io crate loader-rs 0.7.0
[INFO] finished tweaking crates.io crate loader-rs 0.7.0
[INFO] tweaked toml for crates.io crate loader-rs 0.7.0 written to /workspace/builds/worker-6/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 }`
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[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded cached_proc_macro_types v0.1.0
[INFO] [stderr]   Downloaded assert-json-diff v2.0.1
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[INFO] [stderr]   Downloaded json-trait-rs v0.11.0
[INFO] [stderr]   Downloaded cached_proc_macro v0.6.1
[INFO] [stderr]   Downloaded mockito v0.30.0
[INFO] [stderr]   Downloaded join-lazy-fmt v0.9.2
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/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] 7eda65ef0d2344951ab884db544cc58b789f67085e0ea7ce4755b1eb6d7acbec
[INFO] running `Command { std: "docker" "start" "-a" "7eda65ef0d2344951ab884db544cc58b789f67085e0ea7ce4755b1eb6d7acbec", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "7eda65ef0d2344951ab884db544cc58b789f67085e0ea7ce4755b1eb6d7acbec", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7eda65ef0d2344951ab884db544cc58b789f67085e0ea7ce4755b1eb6d7acbec", kill_on_drop: false }`
[INFO] [stdout] 7eda65ef0d2344951ab884db544cc58b789f67085e0ea7ce4755b1eb6d7acbec
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/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] 2fd6c0681eb3571e381cd1d8328286e92958636abaa6c64e883d8748f799a2af
[INFO] running `Command { std: "docker" "start" "-a" "2fd6c0681eb3571e381cd1d8328286e92958636abaa6c64e883d8748f799a2af", kill_on_drop: false }`
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[INFO] [stderr]    Compiling tower-service v0.3.1
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[INFO] [stderr]    Compiling tokio-util v0.3.1
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[INFO] [stderr]    Compiling strum_macros v0.21.1
[INFO] [stderr]    Compiling darling_macro v0.10.2
[INFO] [stderr]    Compiling darling v0.10.2
[INFO] [stderr]    Compiling cached_proc_macro v0.6.1
[INFO] [stderr]    Compiling pin-project v1.0.8
[INFO] [stderr]    Compiling tracing-futures v0.2.5
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[INFO] [stderr]    Compiling loader-rs v0.7.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> src/lib.rs:43:1
[INFO] [stdout]    |
[INFO] [stdout] 43 | #![feature(specialization)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the feature `specialization` is incomplete and may not be safe to use and/or cause compiler crashes
[INFO] [stdout]   --> src/lib.rs:43:12
[INFO] [stdout]    |
[INFO] [stdout] 43 | #![feature(specialization)]
[INFO] [stdout]    |            ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] note: the lint level is defined here
[INFO] [stdout]   --> src/lib.rs:36:5
[INFO] [stdout]    |
[INFO] [stdout] 36 |     warnings,
[INFO] [stdout]    |     ^^^^^^^^
[INFO] [stdout]    = note: `#[warn(incomplete_features)]` implied by `#[warn(warnings)]`
[INFO] [stdout]    = note: see issue #31844 <https://github.com/rust-lang/rust/issues/31844> for more information
[INFO] [stdout]    = help: consider using `min_specialization` instead, which is more stable and complete
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error; 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 `loader-rs` due to 2 previous errors; 1 warning emitted
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "2fd6c0681eb3571e381cd1d8328286e92958636abaa6c64e883d8748f799a2af", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2fd6c0681eb3571e381cd1d8328286e92958636abaa6c64e883d8748f799a2af", kill_on_drop: false }`
[INFO] [stdout] 2fd6c0681eb3571e381cd1d8328286e92958636abaa6c64e883d8748f799a2af