[INFO] fetching crate mussh 3.1.2...
[INFO] testing mussh-3.1.2 against 1.49.0 for beta-1.50-1
[INFO] extracting crate mussh 3.1.2 into /workspace/builds/worker-13/source
[INFO] validating manifest of crates.io crate mussh 3.1.2 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 mussh 3.1.2
[INFO] finished tweaking crates.io crate mussh 3.1.2
[INFO] tweaked toml for crates.io crate mussh 3.1.2 written to /workspace/builds/worker-13/source/Cargo.toml
[INFO] crate crates.io crate mussh 3.1.2 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] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/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] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 7601e39b7549d0c11a55e40f49b509bd6f6065bd6da2fe1572ebb79405d43d32
[INFO] running `Command { std: "docker" "start" "-a" "7601e39b7549d0c11a55e40f49b509bd6f6065bd6da2fe1572ebb79405d43d32", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "7601e39b7549d0c11a55e40f49b509bd6f6065bd6da2fe1572ebb79405d43d32", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7601e39b7549d0c11a55e40f49b509bd6f6065bd6da2fe1572ebb79405d43d32", kill_on_drop: false }`
[INFO] [stdout] 7601e39b7549d0c11a55e40f49b509bd6f6065bd6da2fe1572ebb79405d43d32
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/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] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 289b36864a1ff03bc6743f0b6076399a1db2ee7d3eb0a95b8f6ec8aacaf599da
[INFO] running `Command { std: "docker" "start" "-a" "289b36864a1ff03bc6743f0b6076399a1db2ee7d3eb0a95b8f6ec8aacaf599da", kill_on_drop: false }`
[INFO] [stderr]    Compiling syn v1.0.17
[INFO] [stderr]    Compiling slog v2.5.2
[INFO] [stderr]    Compiling lazy_static v1.2.0
[INFO] [stderr]    Compiling serde v1.0.106
[INFO] [stderr]    Compiling wait_group v0.1.4
[INFO] [stderr]    Compiling num-integer v0.1.42
[INFO] [stderr]    Compiling libz-sys v1.0.25
[INFO] [stderr]    Compiling proc-macro-error-attr v0.4.12
[INFO] [stderr]    Compiling libssh2-sys v0.2.16
[INFO] [stderr]    Compiling proc-macro-error v0.4.12
[INFO] [stderr]    Compiling libsqlite3-sys v0.17.2
[INFO] [stderr]    Compiling proc-macro2 v1.0.10
[INFO] [stderr]    Compiling openssl-sys v0.9.54
[INFO] [stderr]    Compiling dirs-sys v0.3.4
[INFO] [stderr]    Compiling parking_lot_core v0.7.0
[INFO] [stderr]    Compiling clap v2.33.0
[INFO] [stderr]    Compiling crossbeam-utils v0.7.2
[INFO] [stderr]    Compiling thread_local v1.0.1
[INFO] [stderr]    Compiling dirs v2.0.2
[INFO] [stderr]    Compiling parking_lot v0.10.0
[INFO] [stderr]    Compiling term v0.6.1
[INFO] [stderr]    Compiling quote v1.0.3
[INFO] [stderr]    Compiling crossbeam-channel v0.4.2
[INFO] [stderr]    Compiling rusqlite v0.21.0
[INFO] [stderr]    Compiling slog-try v0.2.0
[INFO] [stderr]    Compiling chrono v0.4.11
[INFO] [stderr]    Compiling slog-async v2.5.0
[INFO] [stderr]    Compiling slog-term v2.5.0
[INFO] [stderr]    Compiling syn-mid v0.5.0
[INFO] [stderr]    Compiling ssh2 v0.8.0
[INFO] [stderr]    Compiling serde_derive v1.0.106
[INFO] [stderr]    Compiling toml v0.5.6
[INFO] [stderr]    Compiling getset v0.1.0
[INFO] [stderr]    Compiling libmussh v1.1.3
[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/libmussh-1.1.3/src/lib.rs:10:1
[INFO] [stdout]    |
[INFO] [stdout] 10 | #![feature(crate_visibility_modifier, error_iter)]
[INFO] [stdout]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[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 `libmussh`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "289b36864a1ff03bc6743f0b6076399a1db2ee7d3eb0a95b8f6ec8aacaf599da", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "289b36864a1ff03bc6743f0b6076399a1db2ee7d3eb0a95b8f6ec8aacaf599da", kill_on_drop: false }`
[INFO] [stdout] 289b36864a1ff03bc6743f0b6076399a1db2ee7d3eb0a95b8f6ec8aacaf599da