[INFO] fetching crate mantle-build 0.2.2...
[INFO] extracting crate mantle-build 0.2.2 into work/ex/beta-1.37-6/sources/1.36.0/reg/mantle-build/0.2.2
[INFO] extracting crate mantle-build 0.2.2 into work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/mantle-build/0.2.2
[INFO] validating manifest of mantle-build-0.2.2 on toolchain 1.36.0
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of mantle-build-0.2.2 on toolchain beta-2019-07-23
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing mantle-build-0.2.2
[INFO] finished frobbing mantle-build-0.2.2
[INFO] frobbed toml for mantle-build-0.2.2 written to work/ex/beta-1.37-6/sources/1.36.0/reg/mantle-build/0.2.2/Cargo.toml
[INFO] started frobbing mantle-build-0.2.2
[INFO] finished frobbing mantle-build-0.2.2
[INFO] frobbed toml for mantle-build-0.2.2 written to work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/mantle-build/0.2.2/Cargo.toml
[INFO] crate mantle-build-0.2.2 already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded mantle v0.2.0
[INFO] [stderr]   Downloaded mantle-rpc v0.1.1
[INFO] [stderr]   Downloaded default-env v0.1.1
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing mantle-build-0.2.2 against beta-2019-07-23 for beta-1.37-6
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.37-6/worker-1/beta-2019-07-23:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/mantle-build/0.2.2:/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" "+beta-2019-07-23" "build" "--frozen"`
[INFO] [stdout] d7741a91eab58c9d3eb081bd650704708938e08fdb5bb0a996178d2ada38d57d
[INFO] running `"docker" "start" "-a" "d7741a91eab58c9d3eb081bd650704708938e08fdb5bb0a996178d2ada38d57d"`
[INFO] [stderr]    Compiling syn v0.15.39
[INFO] [stderr]    Compiling winapi v0.3.7
[INFO] [stderr]    Compiling log v0.4.6
[INFO] [stderr]    Compiling backtrace-sys v0.1.30
[INFO] [stderr]    Compiling arrayvec v0.4.10
[INFO] [stderr]    Compiling cgmath v0.16.1
[INFO] [stderr]    Compiling crossbeam-epoch v0.7.1
[INFO] [stderr]    Compiling backtrace v0.3.32
[INFO] [stderr]    Compiling crossbeam-deque v0.6.3
[INFO] [stderr]    Compiling rayon-core v1.5.0
[INFO] [stderr]    Compiling rayon v1.1.0
[INFO] [stderr]    Compiling winconsole v0.10.0
[INFO] [stderr]    Compiling colored v1.8.0
[INFO] [stderr]    Compiling id-arena v2.2.1
[INFO] [stderr]    Compiling synstructure v0.10.2
[INFO] [stderr]    Compiling serde_derive v1.0.94
[INFO] [stderr]    Compiling walrus-macro v0.8.0
[INFO] [stderr]    Compiling proc-macro-hack v0.5.8
[INFO] [stderr]    Compiling proc-quote-impl v0.2.2
[INFO] [stderr]    Compiling failure_derive v0.1.5
[INFO] [stderr]    Compiling proc-quote v0.2.2
[INFO] [stderr]    Compiling failure v0.1.5
[INFO] [stderr]    Compiling walrus v0.8.0
[INFO] [stderr]    Compiling serde v1.0.94
[INFO] [stderr]    Compiling serde_json v1.0.40
[INFO] [stderr]    Compiling toml v0.5.1
[INFO] [stderr]    Compiling mantle-rpc v0.1.1
[INFO] [stderr] error[E0554]: #![feature] may not be used on the beta release channel
[INFO] [stderr]  --> /opt/crater/cargo-home/registry/src/github.com-1ecc6299db9ec823/mantle-rpc-0.1.1/src/lib.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(box_syntax)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0554`.
[INFO] [stderr] error: Could not compile `mantle-rpc`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "d7741a91eab58c9d3eb081bd650704708938e08fdb5bb0a996178d2ada38d57d"`
[INFO] running `"docker" "rm" "-f" "d7741a91eab58c9d3eb081bd650704708938e08fdb5bb0a996178d2ada38d57d"`
[INFO] [stdout] d7741a91eab58c9d3eb081bd650704708938e08fdb5bb0a996178d2ada38d57d