[INFO] fetching crate kakao-rs 0.3.1...
[INFO] testing kakao-rs-0.3.1 against 1.60.0 for beta-1.61-1
[INFO] extracting crate kakao-rs 0.3.1 into /workspace/builds/worker-19/source
[INFO] validating manifest of crates.io crate kakao-rs 0.3.1 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 kakao-rs 0.3.1
[INFO] removed 0 missing examples
[INFO] finished tweaking crates.io crate kakao-rs 0.3.1
[INFO] tweaked toml for crates.io crate kakao-rs 0.3.1 written to /workspace/builds/worker-19/source/Cargo.toml
[INFO] crate crates.io crate kakao-rs 0.3.1 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] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-19/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-19/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] f397b90509cc8a6d7ad9b4aeaf1d5837d5a699a4ac39faa993ac353d0060b812
[INFO] running `Command { std: "docker" "start" "-a" "f397b90509cc8a6d7ad9b4aeaf1d5837d5a699a4ac39faa993ac353d0060b812", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "f397b90509cc8a6d7ad9b4aeaf1d5837d5a699a4ac39faa993ac353d0060b812", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f397b90509cc8a6d7ad9b4aeaf1d5837d5a699a4ac39faa993ac353d0060b812", kill_on_drop: false }`
[INFO] [stdout] f397b90509cc8a6d7ad9b4aeaf1d5837d5a699a4ac39faa993ac353d0060b812
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-19/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-19/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] b1e1ede7c59b4d388fe3b3155e634d85f8a2a4a246a8927cbd1b4fda850ff117
[INFO] running `Command { std: "docker" "start" "-a" "b1e1ede7c59b4d388fe3b3155e634d85f8a2a4a246a8927cbd1b4fda850ff117", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.28
[INFO] [stderr]    Compiling syn v1.0.74
[INFO] [stderr]    Compiling ryu v1.0.5
[INFO] [stderr]    Compiling serde_json v1.0.79
[INFO] [stderr]    Compiling quote v1.0.9
[INFO] [stderr]    Compiling serde_derive v1.0.136
[INFO] [stderr]    Compiling serde v1.0.136
[INFO] [stderr]    Compiling kakao-rs v0.3.1 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> src/lib.rs:41:1
[INFO] [stdout]    |
[INFO] [stdout] 41 | #![feature(proc_macro_hygiene, decl_macro)]
[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 `kakao-rs` due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "b1e1ede7c59b4d388fe3b3155e634d85f8a2a4a246a8927cbd1b4fda850ff117", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b1e1ede7c59b4d388fe3b3155e634d85f8a2a4a246a8927cbd1b4fda850ff117", kill_on_drop: false }`
[INFO] [stdout] b1e1ede7c59b4d388fe3b3155e634d85f8a2a4a246a8927cbd1b4fda850ff117