[INFO] fetching crate plex 0.2.5...
[INFO] testing plex-0.2.5 against 1.55.0 for beta-1.56-1
[INFO] extracting crate plex 0.2.5 into /workspace/builds/worker-109/source
[INFO] validating manifest of crates.io crate plex 0.2.5 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] started tweaking crates.io crate plex 0.2.5
[INFO] finished tweaking crates.io crate plex 0.2.5
[INFO] tweaked toml for crates.io crate plex 0.2.5 written to /workspace/builds/worker-109/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] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-109/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-109/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] 310db067d51c16de5ff3c153cb675f5f8c2757d20e986009d82c28cf382ec9a1
[INFO] running `Command { std: "docker" "start" "-a" "310db067d51c16de5ff3c153cb675f5f8c2757d20e986009d82c28cf382ec9a1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "310db067d51c16de5ff3c153cb675f5f8c2757d20e986009d82c28cf382ec9a1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "310db067d51c16de5ff3c153cb675f5f8c2757d20e986009d82c28cf382ec9a1", kill_on_drop: false }`
[INFO] [stdout] 310db067d51c16de5ff3c153cb675f5f8c2757d20e986009d82c28cf382ec9a1
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-109/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-109/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] 96134b87d9e1d9df2c5147b7055999e1be6cffc8560f19800285ba8ddc45fcef
[INFO] running `Command { std: "docker" "start" "-a" "96134b87d9e1d9df2c5147b7055999e1be6cffc8560f19800285ba8ddc45fcef", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling proc-macro2 v0.4.30
[INFO] [stderr]    Compiling unicode-xid v0.1.0
[INFO] [stderr]    Compiling bit-vec v0.4.4
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling vec_map v0.6.0
[INFO] [stderr]    Compiling lalr v0.0.2
[INFO] [stderr]    Compiling bit-set v0.4.0
[INFO] [stderr]    Compiling redfa v0.0.2
[INFO] [stderr]    Compiling quote v0.6.13
[INFO] [stderr]    Compiling plex v0.2.5 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(proc_macro_diagnostic)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:3:1
[INFO] [stdout]   |
[INFO] [stdout] 3 | #![feature(proc_macro_span)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 previous errors
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `plex` due to 3 previous errors
[INFO] running `Command { std: "docker" "inspect" "96134b87d9e1d9df2c5147b7055999e1be6cffc8560f19800285ba8ddc45fcef", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "96134b87d9e1d9df2c5147b7055999e1be6cffc8560f19800285ba8ddc45fcef", kill_on_drop: false }`
[INFO] [stdout] 96134b87d9e1d9df2c5147b7055999e1be6cffc8560f19800285ba8ddc45fcef