[INFO] updating cached repository udoprog/futures-option
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/udoprog/futures-option
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/udoprog/futures-option" "work/ex/beta-1.38-1/sources/1.37.0/gh/udoprog/futures-option"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/udoprog/futures-option'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/udoprog/futures-option" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/udoprog/futures-option"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/udoprog/futures-option'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 1f8eecedd5b1280997e239813db0642c629a2d16
[INFO] sha for GitHub repo udoprog/futures-option: 1f8eecedd5b1280997e239813db0642c629a2d16
[INFO] validating manifest of udoprog/futures-option 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 udoprog/futures-option 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 udoprog/futures-option
[INFO] finished frobbing udoprog/futures-option
[INFO] frobbed toml for udoprog/futures-option written to work/ex/beta-1.38-1/sources/1.37.0/gh/udoprog/futures-option/Cargo.toml
[INFO] started frobbing udoprog/futures-option
[INFO] finished frobbing udoprog/futures-option
[INFO] frobbed toml for udoprog/futures-option written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/udoprog/futures-option/Cargo.toml
[INFO] crate udoprog/futures-option already has a lockfile, it will not be regenerated
[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 udoprog/futures-option 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-2/beta-2019-08-13:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/udoprog/futures-option:/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] 7428d84275b4d20f62eeb056c57993c6127ded486ee6dca0527a999cd94f1eda
[INFO] running `"docker" "start" "-a" "7428d84275b4d20f62eeb056c57993c6127ded486ee6dca0527a999cd94f1eda"`
[INFO] [stderr]    Compiling syn v0.15.39
[INFO] [stderr]    Compiling proc-macro-nested v0.1.3
[INFO] [stderr]    Compiling futures-core-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling futures-io-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling pin-utils v0.1.0-alpha.4
[INFO] [stderr]    Compiling lazy_static v1.3.0
[INFO] [stderr]    Compiling rand_chacha v0.2.0
[INFO] [stderr]    Compiling getrandom v0.1.6
[INFO] [stderr]    Compiling c2-chacha v0.2.2
[INFO] [stderr]    Compiling futures-sink-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling rand_core v0.5.0
[INFO] [stderr]    Compiling futures-channel-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling rand v0.7.0
[INFO] [stderr]    Compiling proc-macro-hack v0.5.8
[INFO] [stderr]    Compiling futures-select-macro-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling futures-util-preview v0.3.0-alpha.17
[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/futures-util-preview-0.3.0-alpha.17/src/lib.rs:4:38
[INFO] [stderr]   |
[INFO] [stderr] 4 | #![cfg_attr(feature = "async-await", feature(async_await))]
[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 `futures-util-preview`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "7428d84275b4d20f62eeb056c57993c6127ded486ee6dca0527a999cd94f1eda"`
[INFO] running `"docker" "rm" "-f" "7428d84275b4d20f62eeb056c57993c6127ded486ee6dca0527a999cd94f1eda"`
[INFO] [stdout] 7428d84275b4d20f62eeb056c57993c6127ded486ee6dca0527a999cd94f1eda