[INFO] crate loosen_map 0.1.1 is already in cache
[INFO] testing loosen_map-0.1.1 against beta-2019-09-28 for beta-1.39-1
[INFO] extracting crate loosen_map 0.1.1 into work/builds/worker-0/source
[INFO] validating manifest of crates.io crate loosen_map 0.1.1 on toolchain beta-2019-09-28
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+beta-2019-09-28" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking crates.io crate loosen_map 0.1.1
[INFO] finished tweaking crates.io crate loosen_map 0.1.1
[INFO] tweaked toml for crates.io crate loosen_map 0.1.1 written to work/builds/worker-0/source/Cargo.toml
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+beta-2019-09-28" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+beta-2019-09-28" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"docker" "create" "-v" "/big/crater/work/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/big/crater/work/builds/worker-0/source:/opt/rustwide/workdir:ro,Z" "-v" "/big/crater/work/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/big/crater/work/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "MAP_USER_ID=1000" "-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" "--network" "none" "rustops/crates-build-env" "/opt/rustwide/cargo-home/bin/cargo" "+beta-2019-09-28" "build" "--frozen"`
[INFO] [stdout] eab72bd61ed8d5d8c8c948bce170aa2360c114b29c2c564173f4eb952d52dde8
[INFO] running `"docker" "start" "-a" "eab72bd61ed8d5d8c8c948bce170aa2360c114b29c2c564173f4eb952d52dde8"`
[INFO] [stderr]    Compiling loosen_map v0.1.1 (/opt/rustwide/workdir)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stderr]  --> src/lib.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(external_doc)]
[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 `loosen_map`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "eab72bd61ed8d5d8c8c948bce170aa2360c114b29c2c564173f4eb952d52dde8"`
[INFO] running `"docker" "rm" "-f" "eab72bd61ed8d5d8c8c948bce170aa2360c114b29c2c564173f4eb952d52dde8"`
[INFO] [stdout] eab72bd61ed8d5d8c8c948bce170aa2360c114b29c2c564173f4eb952d52dde8