[INFO] crate std_detect 0.1.5 is already in cache
[INFO] extracting crate std_detect 0.1.5 into work/ex/beta-1.38-1/sources/1.37.0/reg/std_detect/0.1.5
[INFO] extracting crate std_detect 0.1.5 into work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/std_detect/0.1.5
[INFO] validating manifest of std_detect-0.1.5 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 std_detect-0.1.5 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 std_detect-0.1.5
[INFO] finished frobbing std_detect-0.1.5
[INFO] frobbed toml for std_detect-0.1.5 written to work/ex/beta-1.38-1/sources/1.37.0/reg/std_detect/0.1.5/Cargo.toml
[INFO] started frobbing std_detect-0.1.5
[INFO] finished frobbing std_detect-0.1.5
[INFO] frobbed toml for std_detect-0.1.5 written to work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/std_detect/0.1.5/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] [stderr]     Blocking waiting for file lock on package cache
[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] [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] testing std_detect-0.1.5 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-5/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/reg/std_detect/0.1.5:/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] e363f5126b18fefe78a386fa7f520f256ceb266c855428373153fa8faa8f89a6
[INFO] running `"docker" "start" "-a" "e363f5126b18fefe78a386fa7f520f256ceb266c855428373153fa8faa8f89a6"`
[INFO] [stderr]    Compiling std_detect v0.1.5 (/opt/crater/workdir)
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]   --> src/lib.rs:15:1
[INFO] [stderr]    |
[INFO] [stderr] 15 | #![feature(const_fn, staged_api, stdsimd, doc_cfg, allow_internal_unstable)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]   --> src/lib.rs:18:34
[INFO] [stderr]    |
[INFO] [stderr] 18 | #![cfg_attr(target_os = "linux", feature(linkage))]
[INFO] [stderr]    |                                  ^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 2 previous errors
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0554`.
[INFO] [stderr] error: Could not compile `std_detect`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "e363f5126b18fefe78a386fa7f520f256ceb266c855428373153fa8faa8f89a6"`
[INFO] running `"docker" "rm" "-f" "e363f5126b18fefe78a386fa7f520f256ceb266c855428373153fa8faa8f89a6"`
[INFO] [stdout] e363f5126b18fefe78a386fa7f520f256ceb266c855428373153fa8faa8f89a6