[INFO] fetching crate mech-program 0.0.5...
[INFO] testing mech-program-0.0.5 against 1.55.0 for beta-1.56-1
[INFO] extracting crate mech-program 0.0.5 into /workspace/builds/worker-77/source
[INFO] validating manifest of crates.io crate mech-program 0.0.5 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 mech-program 0.0.5
[INFO] finished tweaking crates.io crate mech-program 0.0.5
[INFO] tweaked toml for crates.io crate mech-program 0.0.5 written to /workspace/builds/worker-77/source/Cargo.toml
[INFO] crate crates.io crate mech-program 0.0.5 already has a lockfile, it will not be regenerated
[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] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded backtrace v0.3.41
[INFO] [stderr]   Downloaded serde_json v1.0.52
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-77/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-77/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] c98380a41bee764003d635d1938f7ff6776db880c1de39a7a6d20e1e60a008dd
[INFO] running `Command { std: "docker" "start" "-a" "c98380a41bee764003d635d1938f7ff6776db880c1de39a7a6d20e1e60a008dd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "c98380a41bee764003d635d1938f7ff6776db880c1de39a7a6d20e1e60a008dd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c98380a41bee764003d635d1938f7ff6776db880c1de39a7a6d20e1e60a008dd", kill_on_drop: false }`
[INFO] [stdout] c98380a41bee764003d635d1938f7ff6776db880c1de39a7a6d20e1e60a008dd
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-77/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-77/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] 8332a6cd7be4f0110f590cad86451772f4649abef57663d11251892f7d7f867f
[INFO] running `Command { std: "docker" "start" "-a" "8332a6cd7be4f0110f590cad86451772f4649abef57663d11251892f7d7f867f", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling libc v0.2.69
[INFO] [stderr]    Compiling cfg-if v0.1.9
[INFO] [stderr]    Compiling autocfg v1.0.0
[INFO] [stderr]    Compiling byteorder v1.3.4
[INFO] [stderr]    Compiling log v0.4.8
[INFO] [stderr]    Compiling futures v0.1.29
[INFO] [stderr]    Compiling proc-macro2 v1.0.12
[INFO] [stderr]    Compiling cc v1.0.52
[INFO] [stderr]    Compiling version_check v0.9.1
[INFO] [stderr]    Compiling syn v1.0.18
[INFO] [stderr]    Compiling either v1.5.3
[INFO] [stderr]    Compiling slab v0.4.2
[INFO] [stderr]    Compiling matches v0.1.8
[INFO] [stderr]    Compiling smallvec v1.4.0
[INFO] [stderr]    Compiling fnv v1.0.6
[INFO] [stderr]    Compiling itoa v0.4.5
[INFO] [stderr]    Compiling serde v1.0.106
[INFO] [stderr]    Compiling pkg-config v0.3.17
[INFO] [stderr]    Compiling typenum v1.12.0
[INFO] [stderr]    Compiling ryu v1.0.4
[INFO] [stderr]    Compiling getrandom v0.1.14
[INFO] [stderr]    Compiling httparse v1.3.4
[INFO] [stderr]    Compiling percent-encoding v2.1.0
[INFO] [stderr]    Compiling openssl v0.10.29
[INFO] [stderr]    Compiling foreign-types-shared v0.1.1
[INFO] [stderr]    Compiling percent-encoding v1.0.1
[INFO] [stderr]    Compiling arrayvec v0.4.12
[INFO] [stderr]    Compiling failure_derive v0.1.8
[INFO] [stderr]    Compiling byte-tools v0.3.1
[INFO] [stderr]    Compiling native-tls v0.2.4
[INFO] [stderr]    Compiling try-lock v0.2.2
[INFO] [stderr]    Compiling regex-syntax v0.6.17
[INFO] [stderr]    Compiling memchr v2.3.3
[INFO] [stderr]    Compiling openssl-probe v0.1.2
[INFO] [stderr]    Compiling ahash v0.3.4
[INFO] [stderr]    Compiling encoding_rs v0.8.22
[INFO] [stderr]    Compiling fake-simd v0.1.2
[INFO] [stderr]    Compiling bytes v0.5.4
[INFO] [stderr]    Compiling static_assertions v0.3.4
[INFO] [stderr]    Compiling opaque-debug v0.2.3
[INFO] [stderr]    Compiling libloading v0.6.2
[INFO] [stderr]    Compiling lazycell v1.2.1
[INFO] [stderr]    Compiling dtoa v0.4.5
[INFO] [stderr]    Compiling mime v0.3.16
[INFO] [stderr]    Compiling base64 v0.11.0
[INFO] [stderr]    Compiling utf-8 v0.7.5
[INFO] [stderr]    Compiling rand_core v0.3.1
[INFO] [stderr]    Compiling lock_api v0.3.4
[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 rand_jitter v0.1.4
[INFO] [stderr]    Compiling miniz_oxide v0.3.6
[INFO] [stderr]    Compiling parking_lot_core v0.6.2
[INFO] [stderr]    Compiling parking_lot v0.9.0
[INFO] [stderr]    Compiling smallvec v0.6.13
[INFO] [stderr]    Compiling lexical-core v0.6.7
[INFO] [stderr]    Compiling hyper v0.12.35
[INFO] [stderr]    Compiling crc32fast v1.2.0
[INFO] [stderr]    Compiling try_from v0.3.2
[INFO] [stderr]    Compiling unicode-normalization v0.1.12
[INFO] [stderr]    Compiling unicode-bidi v0.3.4
[INFO] [stderr]    Compiling block-padding v0.1.5
[INFO] [stderr]    Compiling rand_xorshift v0.1.1
[INFO] [stderr]    Compiling rand_hc v0.1.0
[INFO] [stderr]    Compiling rand_isaac v0.1.1
[INFO] [stderr]    Compiling foreign-types v0.3.2
[INFO] [stderr]    Compiling crossbeam-utils v0.7.2
[INFO] [stderr]    Compiling memoffset v0.5.4
[INFO] [stderr]    Compiling crossbeam-epoch v0.8.2
[INFO] [stderr]    Compiling indexmap v1.3.2
[INFO] [stderr]    Compiling hashbrown v0.7.2
[INFO] [stderr]    Compiling unicase v2.6.0
[INFO] [stderr]    Compiling error-chain v0.12.2
[INFO] [stderr]    Compiling nom v5.1.1
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]   --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/hashbrown-0.7.2/src/lib.rs:15:5
[INFO] [stdout]    |
[INFO] [stdout] 15 | /     feature(
[INFO] [stdout] 16 | |         alloc_layout_extra,
[INFO] [stdout] 17 | |         allocator_api,
[INFO] [stdout] 18 | |         ptr_offset_from,
[INFO] [stdout] ...  |
[INFO] [stdout] 22 | |         specialization,
[INFO] [stdout] 23 | |     )
[INFO] [stdout]    | |_____^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `hashbrown` due to 2 previous errors
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "8332a6cd7be4f0110f590cad86451772f4649abef57663d11251892f7d7f867f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8332a6cd7be4f0110f590cad86451772f4649abef57663d11251892f7d7f867f", kill_on_drop: false }`
[INFO] [stdout] 8332a6cd7be4f0110f590cad86451772f4649abef57663d11251892f7d7f867f