[INFO] fetching crate phlow-extensions 2.0.0...
[INFO] testing phlow-extensions-2.0.0 against 1.91.0 for beta-1.92-2
[INFO] extracting crate phlow-extensions 2.0.0 into /workspace/builds/worker-3-tc1/source
[INFO] started tweaking crates.io crate phlow-extensions 2.0.0
[INFO] finished tweaking crates.io crate phlow-extensions 2.0.0
[INFO] tweaked toml for crates.io crate phlow-extensions 2.0.0 written to /workspace/builds/worker-3-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate phlow-extensions 2.0.0 on toolchain 1.91.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.91.0" "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" "+1.91.0" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 26 packages to latest compatible versions
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.91.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded phlow-derive v2.0.0
[INFO] [stderr]   Downloaded rust-format v0.3.4
[INFO] [stderr]   Downloaded phlow v2.0.1
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+1.91.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] d4fc895b744ae4e8bf90d5c4ed7ddb5b8cd409e8b0ed5045cff1c763624a4034
[INFO] running `Command { std: "docker" "start" "-a" "d4fc895b744ae4e8bf90d5c4ed7ddb5b8cd409e8b0ed5045cff1c763624a4034", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "d4fc895b744ae4e8bf90d5c4ed7ddb5b8cd409e8b0ed5045cff1c763624a4034", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d4fc895b744ae4e8bf90d5c4ed7ddb5b8cd409e8b0ed5045cff1c763624a4034", kill_on_drop: false }`
[INFO] [stdout] d4fc895b744ae4e8bf90d5c4ed7ddb5b8cd409e8b0ed5045cff1c763624a4034
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+1.91.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 161b4c7ce42c59a5f170ac214c655d1ddbfdecc376f82885cd58fdcd8baf7ed8
[INFO] running `Command { std: "docker" "start" "-a" "161b4c7ce42c59a5f170ac214c655d1ddbfdecc376f82885cd58fdcd8baf7ed8", kill_on_drop: false }`
[INFO] [stderr]    Compiling futures-macro v0.3.31
[INFO] [stderr]    Compiling rust-format v0.3.4
[INFO] [stderr]    Compiling parking_lot_core v0.9.12
[INFO] [stderr]    Compiling phlow-derive v2.0.0
[INFO] [stderr]    Compiling parking_lot v0.12.5
[INFO] [stderr]    Compiling futures-util v0.3.31
[INFO] [stderr]    Compiling futures-executor v0.3.31
[INFO] [stderr]    Compiling phlow v2.0.1
[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/phlow-2.0.1/src/lib.rs:4:35
[INFO] [stdout]   |
[INFO] [stdout] 4 | #![cfg_attr(feature = "printing", feature(specialization))]
[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 `phlow` (lib) due to 1 previous error
[INFO] running `Command { std: "docker" "inspect" "161b4c7ce42c59a5f170ac214c655d1ddbfdecc376f82885cd58fdcd8baf7ed8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "161b4c7ce42c59a5f170ac214c655d1ddbfdecc376f82885cd58fdcd8baf7ed8", kill_on_drop: false }`
[INFO] [stdout] 161b4c7ce42c59a5f170ac214c655d1ddbfdecc376f82885cd58fdcd8baf7ed8