[INFO] cloning repository https://github.com/benmkw/zpng_rs
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/benmkw/zpng_rs" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbenmkw%2Fzpng_rs", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbenmkw%2Fzpng_rs'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 3a68240b049cf875c259ef20126395055dcd85b6
[INFO] testing benmkw/zpng_rs against 1.49.0 for beta-1.50-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fbenmkw%2Fzpng_rs" "/workspace/builds/worker-9/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-9/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/benmkw/zpng_rs 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 git repo https://github.com/benmkw/zpng_rs
[INFO] finished tweaking git repo https://github.com/benmkw/zpng_rs
[INFO] tweaked toml for git repo https://github.com/benmkw/zpng_rs written to /workspace/builds/worker-9/source/Cargo.toml
[INFO] crate git repo https://github.com/benmkw/zpng_rs 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-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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] 2354ec4ed1e4d5bee1090926a58391b5366a6e219208e4f4c09ece985cdec03f
[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" "2354ec4ed1e4d5bee1090926a58391b5366a6e219208e4f4c09ece985cdec03f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "2354ec4ed1e4d5bee1090926a58391b5366a6e219208e4f4c09ece985cdec03f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2354ec4ed1e4d5bee1090926a58391b5366a6e219208e4f4c09ece985cdec03f", kill_on_drop: false }`
[INFO] [stdout] 2354ec4ed1e4d5bee1090926a58391b5366a6e219208e4f4c09ece985cdec03f
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-9/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] 8391916e5aa2420e1fc276000fd4b0d0473b27da4a07244e689414559ba95f7c
[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" "8391916e5aa2420e1fc276000fd4b0d0473b27da4a07244e689414559ba95f7c", kill_on_drop: false }`
[INFO] [stderr]    Compiling rayon-core v1.8.1
[INFO] [stderr]    Compiling syn v1.0.45
[INFO] [stderr]    Compiling argh_shared v0.1.1
[INFO] [stderr]    Compiling object v0.21.1
[INFO] [stderr]    Compiling weezl v0.1.1
[INFO] [stderr]    Compiling rayon v1.4.1
[INFO] [stderr]    Compiling num-rational v0.3.0
[INFO] [stderr]    Compiling num-iter v0.1.41
[INFO] [stderr]    Compiling jobserver v0.1.21
[INFO] [stderr]    Compiling crossbeam-channel v0.4.4
[INFO] [stderr]    Compiling num_cpus v1.13.0
[INFO] [stderr]    Compiling png v0.16.7
[INFO] [stderr]    Compiling cc v1.0.61
[INFO] [stderr]    Compiling gif v0.11.1
[INFO] [stderr]    Compiling zstd-sys v1.4.17+zstd.1.4.5
[INFO] [stderr]    Compiling backtrace v0.3.53
[INFO] [stderr]    Compiling argh_derive v0.1.1
[INFO] [stderr]    Compiling color-backtrace v0.4.2
[INFO] [stderr]    Compiling jpeg-decoder v0.1.20
[INFO] [stderr]    Compiling argh v0.1.3
[INFO] [stderr]    Compiling image v0.23.10
[INFO] [stderr]    Compiling zstd-safe v2.0.5+zstd.1.4.5
[INFO] [stderr]    Compiling zstd v0.5.3+zstd.1.4.5
[INFO] [stderr]    Compiling zpng_rs v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:7:1
[INFO] [stdout]   |
[INFO] [stdout] 7 | #![feature(const_generics)]
[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 `zpng_rs`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "8391916e5aa2420e1fc276000fd4b0d0473b27da4a07244e689414559ba95f7c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8391916e5aa2420e1fc276000fd4b0d0473b27da4a07244e689414559ba95f7c", kill_on_drop: false }`
[INFO] [stdout] 8391916e5aa2420e1fc276000fd4b0d0473b27da4a07244e689414559ba95f7c