[INFO] fetching crate libghost 0.4.6...
[INFO] testing libghost-0.4.6 against 1.90.0 for beta-1.91-3
[INFO] extracting crate libghost 0.4.6 into /workspace/builds/worker-1-tc1/source
[INFO] started tweaking crates.io crate libghost 0.4.6
[INFO] finished tweaking crates.io crate libghost 0.4.6
[INFO] tweaked toml for crates.io crate libghost 0.4.6 written to /workspace/builds/worker-1-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate libghost 0.4.6 on toolchain 1.90.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 43 packages to latest compatible versions
[INFO] [stderr]       Adding pros v0.8.0 (available: v0.9.0)
[INFO] [stderr]       Adding pros-core v0.1.0 (available: v0.1.1)
[INFO] [stderr]       Adding pros-panic v0.1.0 (available: v0.1.1)
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded pros-math v0.1.0
[INFO] [stderr]   Downloaded no_std_io v0.6.0
[INFO] [stderr]   Downloaded pros-panic v0.1.0
[INFO] [stderr]   Downloaded dlmalloc v0.2.11
[INFO] [stderr]   Downloaded pros v0.8.0
[INFO] [stderr]   Downloaded pros-core v0.1.0
[INFO] [stderr]   Downloaded pros-async v0.1.0
[INFO] [stderr]   Downloaded pros-devices v0.1.0
[INFO] [stderr]   Downloaded pros-sys v0.7.0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+1.90.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] c7b7ab710d5ebb6200392bc495592b86ab3e3a2031b0c42c66ecd565d4687572
[INFO] running `Command { std: "docker" "start" "-a" "c7b7ab710d5ebb6200392bc495592b86ab3e3a2031b0c42c66ecd565d4687572", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "c7b7ab710d5ebb6200392bc495592b86ab3e3a2031b0c42c66ecd565d4687572", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c7b7ab710d5ebb6200392bc495592b86ab3e3a2031b0c42c66ecd565d4687572", kill_on_drop: false }`
[INFO] [stdout] c7b7ab710d5ebb6200392bc495592b86ab3e3a2031b0c42c66ecd565d4687572
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/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" "RUSTDOCFLAGS=--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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+1.90.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] d98c978673162871f9a84825472a09c230f4e617fc946b4398886edbd2a040e9
[INFO] running `Command { std: "docker" "start" "-a" "d98c978673162871f9a84825472a09c230f4e617fc946b4398886edbd2a040e9", kill_on_drop: false }`
[INFO] [stderr]    Compiling num-traits v0.2.19
[INFO] [stderr]    Compiling async-task v4.7.1
[INFO] [stderr]    Compiling waker-fn v1.2.0
[INFO] [stderr]    Compiling pros-sys v0.7.0
[INFO] [stderr]    Compiling no_std_io v0.6.0
[INFO] [stderr]    Compiling snafu-derive v0.8.9
[INFO] [stderr]    Compiling num-integer v0.1.46
[INFO] [stderr]    Compiling num-complex v0.4.6
[INFO] [stderr]    Compiling num-iter v0.1.45
[INFO] [stderr]    Compiling num-rational v0.4.2
[INFO] [stderr]    Compiling num v0.4.3
[INFO] [stderr]    Compiling snafu v0.8.9
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/snafu-0.8.9/src/lib.rs:5:46
[INFO] [stdout]   |
[INFO] [stdout] 5 | #![cfg_attr(feature = "unstable-core-error", feature(error_in_core))]
[INFO] [stdout]   |                                              ^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `snafu` (lib) due to 1 previous error
[INFO] running `Command { std: "docker" "inspect" "d98c978673162871f9a84825472a09c230f4e617fc946b4398886edbd2a040e9", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d98c978673162871f9a84825472a09c230f4e617fc946b4398886edbd2a040e9", kill_on_drop: false }`
[INFO] [stdout] d98c978673162871f9a84825472a09c230f4e617fc946b4398886edbd2a040e9