[INFO] fetching crate mech-program 0.0.5...
[INFO] testing mech-program-0.0.5 against 1.49.0 for beta-1.50-1
[INFO] extracting crate mech-program 0.0.5 into /workspace/builds/worker-2/source
[INFO] validating manifest of crates.io crate mech-program 0.0.5 on toolchain 1.49.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "read-manifest" "--manifest-path" "Cargo.toml", 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-2/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" "+1.49.0" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/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" "rustops/crates-build-env@sha256:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] ddfb7c2078687bf3a0360c40d4ebd210ac7925da1c1c3e91185287841fb2923c
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "ddfb7c2078687bf3a0360c40d4ebd210ac7925da1c1c3e91185287841fb2923c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "ddfb7c2078687bf3a0360c40d4ebd210ac7925da1c1c3e91185287841fb2923c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ddfb7c2078687bf3a0360c40d4ebd210ac7925da1c1c3e91185287841fb2923c", kill_on_drop: false }`
[INFO] [stdout] ddfb7c2078687bf3a0360c40d4ebd210ac7925da1c1c3e91185287841fb2923c
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2/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" "rustops/crates-build-env@sha256:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 34aa4757ea695697b82c08971a12e704f05e19d98197f80791ae27d11ed6a6f6
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "34aa4757ea695697b82c08971a12e704f05e19d98197f80791ae27d11ed6a6f6", kill_on_drop: false }`
[INFO] [stderr]    Compiling proc-macro2 v1.0.12
[INFO] [stderr]    Compiling syn v1.0.18
[INFO] [stderr]    Compiling serde v1.0.106
[INFO] [stderr]    Compiling ryu v1.0.4
[INFO] [stderr]    Compiling getrandom v0.1.14
[INFO] [stderr]    Compiling arrayvec v0.4.12
[INFO] [stderr]    Compiling ppv-lite86 v0.2.6
[INFO] [stderr]    Compiling regex-syntax v0.6.17
[INFO] [stderr]    Compiling memchr v2.3.3
[INFO] [stderr]    Compiling ahash v0.3.4
[INFO] [stderr]    Compiling static_assertions v0.3.4
[INFO] [stderr]    Compiling libloading v0.6.2
[INFO] [stderr]    Compiling backtrace-sys v0.1.37
[INFO] [stderr]    Compiling error-chain v0.12.2
[INFO] [stderr]    Compiling hashbrown v0.7.2
[INFO] [stderr]    Compiling nom v5.1.1
[INFO] [stderr]    Compiling try_from v0.3.2
[INFO] [stderr]    Compiling miniz_oxide v0.3.6
[INFO] [stderr]    Compiling input_buffer v0.3.1
[INFO] [stderr]    Compiling log v0.4.8
[INFO] [stderr]    Compiling crc32fast v1.2.0
[INFO] [stderr]    Compiling encoding_rs v0.8.22
[INFO] [stderr]    Compiling net2 v0.2.34
[INFO] [stderr]    Compiling atty v0.2.14
[INFO] [stderr]    Compiling lexical-core v0.6.7
[INFO] [stderr]    Compiling crossbeam-utils v0.7.2
[INFO] [stderr]    Compiling bytes v0.4.12
[INFO] [stderr]    Compiling futures-cpupool v0.1.8
[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] [stderr]    Compiling want v0.2.0
[INFO] [stderr]    Compiling colored v1.9.3
[INFO] [stderr]    Compiling cookie v0.12.0
[INFO] [stderr]    Compiling openssl v0.10.29
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `hashbrown`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "34aa4757ea695697b82c08971a12e704f05e19d98197f80791ae27d11ed6a6f6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "34aa4757ea695697b82c08971a12e704f05e19d98197f80791ae27d11ed6a6f6", kill_on_drop: false }`
[INFO] [stdout] 34aa4757ea695697b82c08971a12e704f05e19d98197f80791ae27d11ed6a6f6