[INFO] crate two-sided-vec 0.1.6 is already in cache
[INFO] extracting crate two-sided-vec 0.1.6 into work/ex/beta-1.38-1/sources/1.37.0/reg/two-sided-vec/0.1.6
[INFO] extracting crate two-sided-vec 0.1.6 into work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/two-sided-vec/0.1.6
[INFO] validating manifest of two-sided-vec-0.1.6 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 two-sided-vec-0.1.6 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 two-sided-vec-0.1.6
[INFO] finished frobbing two-sided-vec-0.1.6
[INFO] frobbed toml for two-sided-vec-0.1.6 written to work/ex/beta-1.38-1/sources/1.37.0/reg/two-sided-vec/0.1.6/Cargo.toml
[INFO] started frobbing two-sided-vec-0.1.6
[INFO] finished frobbing two-sided-vec-0.1.6
[INFO] frobbed toml for two-sided-vec-0.1.6 written to work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/two-sided-vec/0.1.6/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 two-sided-vec-0.1.6 against beta-2019-08-13 for beta-1.38-1
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.38-1/worker-4/beta-2019-08-13:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/two-sided-vec/0.1.6:/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-2019-08-13" "build" "--frozen"`
[INFO] [stdout] 3dd40d338f7e4a4bffcc6193b6eb4a34bc19d57f4eb9deb6aca86b1845a3414d
[INFO] running `"docker" "start" "-a" "3dd40d338f7e4a4bffcc6193b6eb4a34bc19d57f4eb9deb6aca86b1845a3414d"`
[INFO] [stderr]    Compiling two-sided-vec v0.1.6 (/opt/crater/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(
[INFO] [stderr] 2 | |     dropck_eyepatch, // Needed to bypass dropchk
[INFO] [stderr] 3 | |     allocator_api, // We need to allocate raw memory
[INFO] [stderr] 4 | |     alloc_layout_extra, // We need to allocate memory
[INFO] [stderr] 5 | |     trusted_len, // Trusted length iterators improve performance
[INFO] [stderr] 6 | |     specialization, // Used to improve extend performance
[INFO] [stderr] 7 | | )]
[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 `two-sided-vec`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "3dd40d338f7e4a4bffcc6193b6eb4a34bc19d57f4eb9deb6aca86b1845a3414d"`
[INFO] running `"docker" "rm" "-f" "3dd40d338f7e4a4bffcc6193b6eb4a34bc19d57f4eb9deb6aca86b1845a3414d"`
[INFO] [stdout] 3dd40d338f7e4a4bffcc6193b6eb4a34bc19d57f4eb9deb6aca86b1845a3414d