[INFO] updating cached repository LooMaclin/tux_async_example
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/LooMaclin/tux_async_example
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/LooMaclin/tux_async_example" "work/ex/beta-1.38-1/sources/1.37.0/gh/LooMaclin/tux_async_example"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/LooMaclin/tux_async_example'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/LooMaclin/tux_async_example" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/LooMaclin/tux_async_example"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/LooMaclin/tux_async_example'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] a42870d0c2d19a9213a03f4c191909d2cce56a64
[INFO] sha for GitHub repo LooMaclin/tux_async_example: a42870d0c2d19a9213a03f4c191909d2cce56a64
[INFO] validating manifest of LooMaclin/tux_async_example 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 LooMaclin/tux_async_example 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 LooMaclin/tux_async_example
[INFO] finished frobbing LooMaclin/tux_async_example
[INFO] frobbed toml for LooMaclin/tux_async_example written to work/ex/beta-1.38-1/sources/1.37.0/gh/LooMaclin/tux_async_example/Cargo.toml
[INFO] started frobbing LooMaclin/tux_async_example
[INFO] finished frobbing LooMaclin/tux_async_example
[INFO] frobbed toml for LooMaclin/tux_async_example written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/LooMaclin/tux_async_example/Cargo.toml
[INFO] crate LooMaclin/tux_async_example 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] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] testing LooMaclin/tux_async_example against 1.37.0 for beta-1.38-1
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.38-1/worker-6/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/gh/LooMaclin/tux_async_example:/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" "+1.37.0" "build" "--frozen"`
[INFO] [stdout] 68ab9e6dce2940137b0b908cdb1a57fac641ffb4751f9dc111bcb35f713854c7
[INFO] running `"docker" "start" "-a" "68ab9e6dce2940137b0b908cdb1a57fac641ffb4751f9dc111bcb35f713854c7"`
[INFO] [stderr]    Compiling futures v0.1.25
[INFO] [stderr]    Compiling crossbeam v0.6.0
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]    --> /opt/crater/cargo-home/registry/src/github.com-1ecc6299db9ec823/futures-0.1.25/src/lib.rs:161:34
[INFO] [stderr]     |
[INFO] [stderr] 161 | #![cfg_attr(feature = "nightly", feature(pin))]
[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`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "68ab9e6dce2940137b0b908cdb1a57fac641ffb4751f9dc111bcb35f713854c7"`
[INFO] running `"docker" "rm" "-f" "68ab9e6dce2940137b0b908cdb1a57fac641ffb4751f9dc111bcb35f713854c7"`
[INFO] [stdout] 68ab9e6dce2940137b0b908cdb1a57fac641ffb4751f9dc111bcb35f713854c7