[INFO] crate plumber-rs 0.1.2 is already in cache
[INFO] extracting crate plumber-rs 0.1.2 into work/ex/beta-1.38-1/sources/1.37.0/reg/plumber-rs/0.1.2
[INFO] extracting crate plumber-rs 0.1.2 into work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/plumber-rs/0.1.2
[INFO] validating manifest of plumber-rs-0.1.2 on toolchain 1.37.0
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of plumber-rs-0.1.2 on toolchain beta-2019-08-13
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing plumber-rs-0.1.2
[INFO] finished frobbing plumber-rs-0.1.2
[INFO] frobbed toml for plumber-rs-0.1.2 written to work/ex/beta-1.38-1/sources/1.37.0/reg/plumber-rs/0.1.2/Cargo.toml
[INFO] started frobbing plumber-rs-0.1.2
[INFO] finished frobbing plumber-rs-0.1.2
[INFO] frobbed toml for plumber-rs-0.1.2 written to work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/plumber-rs/0.1.2/Cargo.toml
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing plumber-rs-0.1.2 against 1.37.0 for beta-1.38-1
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.38-1/worker-0/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/reg/plumber-rs/0.1.2:/opt/crater/workdir:ro,Z" "-v" "/mnt/big/crater/work/local/cargo-home:/opt/crater/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/local/rustup-home:/opt/crater/rustup-home:ro,Z" "-e" "USER_ID=1000" "-e" "SOURCE_DIR=/opt/crater/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/crater/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/crater/cargo-home" "-e" "RUSTUP_HOME=/opt/crater/rustup-home" "-w" "/opt/crater/workdir" "-m" "1536M" "--network" "none" "rustops/crates-build-env" "/opt/crater/cargo-home/bin/cargo" "+1.37.0" "build" "--frozen"`
[INFO] [stdout] cae538d6924c1abae10921a611f6ff411028accc62cfddb3ef5955bb16ba6cdf
[INFO] running `"docker" "start" "-a" "cae538d6924c1abae10921a611f6ff411028accc62cfddb3ef5955bb16ba6cdf"`
[INFO] [stderr]    Compiling plumber-rs v0.1.2 (/opt/crater/workdir)
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]  --> src/lib.rs:2:1
[INFO] [stderr]   |
[INFO] [stderr] 2 | #![feature(box_leak)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]  --> src/lib.rs:3:1
[INFO] [stderr]   |
[INFO] [stderr] 3 | #![feature(associated_type_defaults)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 2 previous errors
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0554`.
[INFO] [stderr] error: Could not compile `plumber-rs`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "cae538d6924c1abae10921a611f6ff411028accc62cfddb3ef5955bb16ba6cdf"`
[INFO] running `"docker" "rm" "-f" "cae538d6924c1abae10921a611f6ff411028accc62cfddb3ef5955bb16ba6cdf"`
[INFO] [stdout] cae538d6924c1abae10921a611f6ff411028accc62cfddb3ef5955bb16ba6cdf