[INFO] crate bitflags-associated-constants 0.6.0 is already in cache
[INFO] extracting crate bitflags-associated-constants 0.6.0 into work/ex/beta-1.38-1/sources/1.37.0/reg/bitflags-associated-constants/0.6.0
[INFO] extracting crate bitflags-associated-constants 0.6.0 into work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/bitflags-associated-constants/0.6.0
[INFO] validating manifest of bitflags-associated-constants-0.6.0 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 bitflags-associated-constants-0.6.0 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 bitflags-associated-constants-0.6.0
[INFO] finished frobbing bitflags-associated-constants-0.6.0
[INFO] frobbed toml for bitflags-associated-constants-0.6.0 written to work/ex/beta-1.38-1/sources/1.37.0/reg/bitflags-associated-constants/0.6.0/Cargo.toml
[INFO] started frobbing bitflags-associated-constants-0.6.0
[INFO] finished frobbing bitflags-associated-constants-0.6.0
[INFO] frobbed toml for bitflags-associated-constants-0.6.0 written to work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/bitflags-associated-constants/0.6.0/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 bitflags-associated-constants-0.6.0 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-5/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/reg/bitflags-associated-constants/0.6.0:/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] 1c5ef858441839ebb5246bc6f31764be7e39e76558e9fb34f8d84a968c004170
[INFO] running `"docker" "start" "-a" "1c5ef858441839ebb5246bc6f31764be7e39e76558e9fb34f8d84a968c004170"`
[INFO] [stderr]    Compiling bitflags-associated-constants v0.6.0 (/opt/crater/workdir)
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]   --> src/lib.rs:11:1
[INFO] [stderr]    |
[INFO] [stderr] 11 | #![feature(associated_consts)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: extern crate `core` is private, and cannot be re-exported (error E0365), consider declaring with `pub`
[INFO] [stderr]   --> src/lib.rs:25:9
[INFO] [stderr]    |
[INFO] [stderr] 25 | pub use core as __core;
[INFO] [stderr]    |         ^^^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: #[warn(pub_use_of_private_extern_crate)] on by default
[INFO] [stderr]    = warning: this was previously accepted by the compiler but is being phased out; it will become a hard error in a future release!
[INFO] [stderr]    = note: for more information, see issue #34537 <https://github.com/rust-lang/rust/issues/34537>
[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 `bitflags-associated-constants`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "1c5ef858441839ebb5246bc6f31764be7e39e76558e9fb34f8d84a968c004170"`
[INFO] running `"docker" "rm" "-f" "1c5ef858441839ebb5246bc6f31764be7e39e76558e9fb34f8d84a968c004170"`
[INFO] [stdout] 1c5ef858441839ebb5246bc6f31764be7e39e76558e9fb34f8d84a968c004170