[INFO] fetching crate khalas 0.2.0...
[INFO] testing khalas-0.2.0 against 1.55.0 for beta-1.56-1
[INFO] extracting crate khalas 0.2.0 into /workspace/builds/worker-26/source
[INFO] validating manifest of crates.io crate khalas 0.2.0 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 khalas 0.2.0
[INFO] finished tweaking crates.io crate khalas 0.2.0
[INFO] tweaked toml for crates.io crate khalas 0.2.0 written to /workspace/builds/worker-26/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] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-26/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-26/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] 035205fe4b21a5c5f5c29c57042436eb88d4ddee798aaefac80d30017f311a11
[INFO] running `Command { std: "docker" "start" "-a" "035205fe4b21a5c5f5c29c57042436eb88d4ddee798aaefac80d30017f311a11", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "035205fe4b21a5c5f5c29c57042436eb88d4ddee798aaefac80d30017f311a11", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "035205fe4b21a5c5f5c29c57042436eb88d4ddee798aaefac80d30017f311a11", kill_on_drop: false }`
[INFO] [stdout] 035205fe4b21a5c5f5c29c57042436eb88d4ddee798aaefac80d30017f311a11
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-26/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-26/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] 2e0068741a64bd842301c7e0e2cf97744fc876910798fe1a7f1787aa72623fd1
[INFO] running `Command { std: "docker" "start" "-a" "2e0068741a64bd842301c7e0e2cf97744fc876910798fe1a7f1787aa72623fd1", kill_on_drop: false }`
[INFO] [stderr]    Compiling autocfg v0.1.7
[INFO] [stderr]    Compiling rand_core v0.4.2
[INFO] [stderr]    Compiling log v0.4.14
[INFO] [stderr]    Compiling libc v0.2.101
[INFO] [stderr]    Compiling wasm-bindgen-shared v0.2.77
[INFO] [stderr]    Compiling serde_derive v1.0.130
[INFO] [stderr]    Compiling bumpalo v3.7.0
[INFO] [stderr]    Compiling serde v1.0.130
[INFO] [stderr]    Compiling ryu v1.0.5
[INFO] [stderr]    Compiling lazy_static v1.4.0
[INFO] [stderr]    Compiling serde_json v1.0.67
[INFO] [stderr]    Compiling wasm-bindgen v0.2.77
[INFO] [stderr]    Compiling itoa v0.4.8
[INFO] [stderr]    Compiling futures-core v0.3.17
[INFO] [stderr]    Compiling memchr v2.4.1
[INFO] [stderr]    Compiling siphasher v0.2.3
[INFO] [stderr]    Compiling version_check v0.9.3
[INFO] [stderr]    Compiling proc-macro2 v0.4.30
[INFO] [stderr]    Compiling futures-channel v0.3.17
[INFO] [stderr]    Compiling futures-task v0.3.17
[INFO] [stderr]    Compiling futures-sink v0.3.17
[INFO] [stderr]    Compiling unicode-xid v0.1.0
[INFO] [stderr]    Compiling slab v0.4.4
[INFO] [stderr]    Compiling unicode-bidi v0.3.6
[INFO] [stderr]    Compiling pin-project-lite v0.2.7
[INFO] [stderr]    Compiling futures-io v0.3.17
[INFO] [stderr]    Compiling matches v0.1.9
[INFO] [stderr]    Compiling version_check v0.1.5
[INFO] [stderr]    Compiling percent-encoding v1.0.1
[INFO] [stderr]    Compiling pulldown-cmark v0.6.1
[INFO] [stderr]    Compiling unicode-width v0.1.8
[INFO] [stderr]    Compiling cfg-if v0.1.10
[INFO] [stderr]    Compiling bitflags v1.3.2
[INFO] [stderr]    Compiling approx v0.1.1
[INFO] [stderr]    Compiling enclose v1.1.8
[INFO] [stderr]    Compiling convert_case v0.4.0
[INFO] [stderr]    Compiling futures-macro v0.3.17
[INFO] [stderr]    Compiling futures-util v0.3.17
[INFO] [stderr]    Compiling num-traits v0.2.14
[INFO] [stderr]    Compiling unicode-normalization v0.1.19
[INFO] [stderr]    Compiling derive_rich v0.2.2
[INFO] [stderr]    Compiling rand_core v0.3.1
[INFO] [stderr]    Compiling rand_jitter v0.1.4
[INFO] [stderr]    Compiling getopts v0.2.21
[INFO] [stderr]    Compiling phf_shared v0.7.24
[INFO] [stderr]    Compiling rand_hc v0.1.0
[INFO] [stderr]    Compiling rand_isaac v0.1.1
[INFO] [stderr]    Compiling rand_xorshift v0.1.1
[INFO] [stderr]    Compiling phf v0.7.24
[INFO] [stderr]    Compiling rand_chacha v0.1.1
[INFO] [stderr]    Compiling rand_pcg v0.1.2
[INFO] [stderr]    Compiling rand v0.6.5
[INFO] [stderr]    Compiling dbg v1.0.4
[INFO] [stderr]    Compiling unicase v2.6.0
[INFO] [stderr]    Compiling seed v0.6.0
[INFO] [stderr]    Compiling derive_more v0.99.16
[INFO] [stderr]    Compiling wasm-bindgen-backend v0.2.77
[INFO] [stderr]    Compiling quote v0.6.13
[INFO] [stderr]    Compiling rand_os v0.1.3
[INFO] [stderr]    Compiling time v0.1.44
[INFO] [stderr]    Compiling idna v0.1.5
[INFO] [stderr]    Compiling syn v0.14.9
[INFO] [stderr]    Compiling url v1.7.2
[INFO] [stderr]    Compiling wasm-bindgen-macro-support v0.2.77
[INFO] [stderr]    Compiling phf_generator v0.7.24
[INFO] [stderr]    Compiling phf_codegen v0.7.24
[INFO] [stderr]    Compiling palette v0.4.1
[INFO] [stderr]    Compiling cookie v0.12.0
[INFO] [stderr]    Compiling wasm-bindgen-macro v0.2.77
[INFO] [stderr]    Compiling palette_derive v0.4.1
[INFO] [stderr]    Compiling futures-executor v0.3.17
[INFO] [stderr]    Compiling futures v0.3.17
[INFO] [stderr]    Compiling js-sys v0.3.54
[INFO] [stderr]    Compiling console_error_panic_hook v0.1.6
[INFO] [stderr]    Compiling web-sys v0.3.54
[INFO] [stderr]    Compiling wasm-bindgen-futures v0.4.27
[INFO] [stderr]    Compiling gloo-timers v0.2.1
[INFO] [stderr]    Compiling khalas v0.2.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(decl_macro)]
[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:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | #![feature(bool_to_option)]
[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 `khalas` due to 3 previous errors
[INFO] running `Command { std: "docker" "inspect" "2e0068741a64bd842301c7e0e2cf97744fc876910798fe1a7f1787aa72623fd1", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2e0068741a64bd842301c7e0e2cf97744fc876910798fe1a7f1787aa72623fd1", kill_on_drop: false }`
[INFO] [stdout] 2e0068741a64bd842301c7e0e2cf97744fc876910798fe1a7f1787aa72623fd1