[INFO] crate gen-stream 0.2.4 is already in cache
[INFO] testing gen-stream-0.2.4 against beta-2019-09-28 for beta-1.39-1
[INFO] extracting crate gen-stream 0.2.4 into work/builds/worker-3/source
[INFO] validating manifest of crates.io crate gen-stream 0.2.4 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 gen-stream 0.2.4
[INFO] finished tweaking crates.io crate gen-stream 0.2.4
[INFO] tweaked toml for crates.io crate gen-stream 0.2.4 written to work/builds/worker-3/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-3/target:/opt/rustwide/target:rw,Z" "-v" "/big/crater/work/builds/worker-3/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] 327239d714c6842d1c6f2fea578e9bd61797e35edb2601dd8b282e9d0859b9b4
[INFO] running `"docker" "start" "-a" "327239d714c6842d1c6f2fea578e9bd61797e35edb2601dd8b282e9d0859b9b4"`
[INFO] [stderr]    Compiling futures-core-preview v0.3.0-alpha.19
[INFO] [stderr]    Compiling gen-stream v0.2.4 (/opt/rustwide/workdir)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stderr]   --> src/lib.rs:67:1
[INFO] [stderr]    |
[INFO] [stderr] 67 | #![feature(generator_trait)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stderr]   --> src/lib.rs:68:1
[INFO] [stderr]    |
[INFO] [stderr] 68 | #![feature(gen_future)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stderr]   --> src/lib.rs:69:1
[INFO] [stderr]    |
[INFO] [stderr] 69 | #![feature(never_type)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 3 previous errors
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0554`.
[INFO] [stderr] error: could not compile `gen-stream`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "327239d714c6842d1c6f2fea578e9bd61797e35edb2601dd8b282e9d0859b9b4"`
[INFO] running `"docker" "rm" "-f" "327239d714c6842d1c6f2fea578e9bd61797e35edb2601dd8b282e9d0859b9b4"`
[INFO] [stdout] 327239d714c6842d1c6f2fea578e9bd61797e35edb2601dd8b282e9d0859b9b4