[INFO] crate mcf-config-demo-settings 0.1.0 is already in cache
[INFO] extracting crate mcf-config-demo-settings 0.1.0 into work/ex/beta-1.38-1/sources/1.37.0/reg/mcf-config-demo-settings/0.1.0
[INFO] extracting crate mcf-config-demo-settings 0.1.0 into work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/mcf-config-demo-settings/0.1.0
[INFO] validating manifest of mcf-config-demo-settings-0.1.0 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 mcf-config-demo-settings-0.1.0 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 mcf-config-demo-settings-0.1.0
[INFO] finished frobbing mcf-config-demo-settings-0.1.0
[INFO] frobbed toml for mcf-config-demo-settings-0.1.0 written to work/ex/beta-1.38-1/sources/1.37.0/reg/mcf-config-demo-settings/0.1.0/Cargo.toml
[INFO] started frobbing mcf-config-demo-settings-0.1.0
[INFO] finished frobbing mcf-config-demo-settings-0.1.0
[INFO] frobbed toml for mcf-config-demo-settings-0.1.0 written to work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/mcf-config-demo-settings/0.1.0/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 mcf-config-demo-settings-0.1.0 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-3/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/reg/mcf-config-demo-settings/0.1.0:/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] 858f89be01387007066794095a56e278727995173a41170a47d4a126e14591aa
[INFO] running `"docker" "start" "-a" "858f89be01387007066794095a56e278727995173a41170a47d4a126e14591aa"`
[INFO] [stderr]    Compiling mcf-config-demo-settings v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]  --> src/lib.rs:2:1
[INFO] [stderr]   |
[INFO] [stderr] 2 | #![feature(min_const_fn)]
[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 `mcf-config-demo-settings`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "858f89be01387007066794095a56e278727995173a41170a47d4a126e14591aa"`
[INFO] running `"docker" "rm" "-f" "858f89be01387007066794095a56e278727995173a41170a47d4a126e14591aa"`
[INFO] [stdout] 858f89be01387007066794095a56e278727995173a41170a47d4a126e14591aa