[INFO] crate tls-async 0.3.0-alpha.7 is already in cache
[INFO] extracting crate tls-async 0.3.0-alpha.7 into work/ex/beta-1.37-6/sources/1.36.0/reg/tls-async/0.3.0-alpha.7
[INFO] extracting crate tls-async 0.3.0-alpha.7 into work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/tls-async/0.3.0-alpha.7
[INFO] validating manifest of tls-async-0.3.0-alpha.7 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 tls-async-0.3.0-alpha.7 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 tls-async-0.3.0-alpha.7
[INFO] finished frobbing tls-async-0.3.0-alpha.7
[INFO] frobbed toml for tls-async-0.3.0-alpha.7 written to work/ex/beta-1.37-6/sources/1.36.0/reg/tls-async/0.3.0-alpha.7/Cargo.toml
[INFO] started frobbing tls-async-0.3.0-alpha.7
[INFO] finished frobbing tls-async-0.3.0-alpha.7
[INFO] frobbed toml for tls-async-0.3.0-alpha.7 written to work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/tls-async/0.3.0-alpha.7/Cargo.toml
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing tls-async-0.3.0-alpha.7 against 1.36.0 for beta-1.37-6
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.37-6/worker-0/1.36.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/1.36.0/reg/tls-async/0.3.0-alpha.7:/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" "+1.36.0" "build" "--frozen"`
[INFO] [stdout] a9f85b5afa778682fb30309538419e4ccd520aec5a2197d572064b963b81746a
[INFO] running `"docker" "start" "-a" "a9f85b5afa778682fb30309538419e4ccd520aec5a2197d572064b963b81746a"`
[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 openssl v0.10.24
[INFO] [stderr]    Compiling failure v0.1.5
[INFO] [stderr]    Compiling futures-sink-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling futures-channel-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling futures-util-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling native-tls v0.2.3
[INFO] [stderr]    Compiling futures-executor-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling futures-preview v0.3.0-alpha.17
[INFO] [stderr]    Compiling tls-async v0.3.0-alpha.7 (/opt/crater/workdir)
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]   --> src/lib.rs:17:1
[INFO] [stderr]    |
[INFO] [stderr] 17 | #![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 `tls-async`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "a9f85b5afa778682fb30309538419e4ccd520aec5a2197d572064b963b81746a"`
[INFO] running `"docker" "rm" "-f" "a9f85b5afa778682fb30309538419e4ccd520aec5a2197d572064b963b81746a"`
[INFO] [stdout] a9f85b5afa778682fb30309538419e4ccd520aec5a2197d572064b963b81746a