[INFO] fetching crate zerogc-simple 0.2.0-alpha.7...
[INFO] testing zerogc-simple-0.2.0-alpha.7 against 1.60.0 for beta-1.61-1
[INFO] extracting crate zerogc-simple 0.2.0-alpha.7 into /workspace/builds/worker-51/source
[INFO] validating manifest of crates.io crate zerogc-simple 0.2.0-alpha.7 on toolchain 1.60.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.60.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate zerogc-simple 0.2.0-alpha.7
[INFO] removed 0 missing tests
[INFO] finished tweaking crates.io crate zerogc-simple 0.2.0-alpha.7
[INFO] tweaked toml for crates.io crate zerogc-simple 0.2.0-alpha.7 written to /workspace/builds/worker-51/source/Cargo.toml
[INFO] crate crates.io crate zerogc-simple 0.2.0-alpha.7 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.60.0" "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 slog-term v2.8.1
[INFO] [stderr]   Downloaded inherent v1.0.0
[INFO] [stderr]   Downloaded zerogc v0.2.0-alpha.7
[INFO] [stderr]   Downloaded proc-macro-kwargs-derive v0.1.5
[INFO] [stderr]   Downloaded proc-macro-kwargs v0.1.5
[INFO] [stderr]   Downloaded zerogc-derive v0.2.0-alpha.6
[INFO] [stderr]   Downloaded zerogc-context v0.2.0-alpha.7
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-51/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-51/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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+1.60.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] ceba60a3ef45c7f095773ebdba199759026e792dbfd69a00162901b45fff1073
[INFO] running `Command { std: "docker" "start" "-a" "ceba60a3ef45c7f095773ebdba199759026e792dbfd69a00162901b45fff1073", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "ceba60a3ef45c7f095773ebdba199759026e792dbfd69a00162901b45fff1073", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ceba60a3ef45c7f095773ebdba199759026e792dbfd69a00162901b45fff1073", kill_on_drop: false }`
[INFO] [stdout] ceba60a3ef45c7f095773ebdba199759026e792dbfd69a00162901b45fff1073
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-51/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-51/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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+1.60.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 7e0ce0f49f74b37a9de8109ea87d7a875ce51caa5941cf4b1f8ce17cd6daa62d
[INFO] running `Command { std: "docker" "start" "-a" "7e0ce0f49f74b37a9de8109ea87d7a875ce51caa5941cf4b1f8ce17cd6daa62d", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling proc-macro2 v1.0.36
[INFO] [stderr]    Compiling syn v1.0.86
[INFO] [stderr]    Compiling unicode-segmentation v1.9.0
[INFO] [stderr]    Compiling ident_case v1.0.1
[INFO] [stderr]    Compiling strsim v0.10.0
[INFO] [stderr]    Compiling libc v0.2.117
[INFO] [stderr]    Compiling either v1.6.1
[INFO] [stderr]    Compiling scopeguard v1.1.0
[INFO] [stderr]    Compiling parking_lot_core v0.8.5
[INFO] [stderr]    Compiling slog v2.7.0
[INFO] [stderr]    Compiling crossbeam-utils v0.8.7
[INFO] [stderr]    Compiling bumpalo v3.9.1
[INFO] [stderr]    Compiling once_cell v1.9.0
[INFO] [stderr]    Compiling indexmap v1.8.0
[INFO] [stderr]    Compiling instant v0.1.12
[INFO] [stderr]    Compiling lock_api v0.4.6
[INFO] [stderr]    Compiling itertools v0.10.3
[INFO] [stderr]    Compiling heck v0.3.3
[INFO] [stderr]    Compiling quote v1.0.15
[INFO] [stderr]    Compiling parking_lot v0.11.2
[INFO] [stderr]    Compiling darling_core v0.13.1
[INFO] [stderr]    Compiling proc-macro-kwargs-derive v0.1.5
[INFO] [stderr]    Compiling inherent v1.0.0
[INFO] [stderr]    Compiling darling_macro v0.13.1
[INFO] [stderr]    Compiling proc-macro-kwargs v0.1.5
[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/proc-macro-kwargs-0.1.5/src/lib.rs:3:1
[INFO] [stdout]   |
[INFO] [stdout] 3 | #![feature(trait_alias)]
[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 `proc-macro-kwargs` due to 2 previous errors
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "7e0ce0f49f74b37a9de8109ea87d7a875ce51caa5941cf4b1f8ce17cd6daa62d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7e0ce0f49f74b37a9de8109ea87d7a875ce51caa5941cf4b1f8ce17cd6daa62d", kill_on_drop: false }`
[INFO] [stdout] 7e0ce0f49f74b37a9de8109ea87d7a875ce51caa5941cf4b1f8ce17cd6daa62d