[INFO] updating cached repository johcar/rust_os
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/johcar/rust_os
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/johcar/rust_os" "work/ex/beta-1.38-1/sources/1.37.0/gh/johcar/rust_os"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/johcar/rust_os'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/johcar/rust_os" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/johcar/rust_os"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/johcar/rust_os'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 69ac5762ada453a4019a30e8eee68d495c209773
[INFO] sha for GitHub repo johcar/rust_os: 69ac5762ada453a4019a30e8eee68d495c209773
[INFO] validating manifest of johcar/rust_os 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 johcar/rust_os 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 johcar/rust_os
[INFO] finished frobbing johcar/rust_os
[INFO] frobbed toml for johcar/rust_os written to work/ex/beta-1.38-1/sources/1.37.0/gh/johcar/rust_os/Cargo.toml
[INFO] started frobbing johcar/rust_os
[INFO] finished frobbing johcar/rust_os
[INFO] frobbed toml for johcar/rust_os written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/johcar/rust_os/Cargo.toml
[INFO] crate johcar/rust_os 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] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing johcar/rust_os 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/gh/johcar/rust_os:/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] 186467f45cfa3867d53ffd7a2545f0685ebf9c5fe41a4d0ed0c29d14ed0ce53e
[INFO] running `"docker" "start" "-a" "186467f45cfa3867d53ffd7a2545f0685ebf9c5fe41a4d0ed0c29d14ed0ce53e"`
[INFO] [stderr]    Compiling rust_os v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] error[E0557]: feature has been removed
[INFO] [stderr]  --> src/main.rs:3:12
[INFO] [stderr]   |
[INFO] [stderr] 3 | #![feature(panic_implementation)]
[INFO] [stderr]   |            ^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr] note: subsumed by `#[panic_handler]`
[INFO] [stderr]  --> src/main.rs:3:12
[INFO] [stderr]   |
[INFO] [stderr] 3 | #![feature(panic_implementation)]
[INFO] [stderr]   |            ^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]  --> src/main.rs:3:1
[INFO] [stderr]   |
[INFO] [stderr] 3 | #![feature(panic_implementation)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 2 previous errors
[INFO] [stderr] 
[INFO] [stderr] Some errors have detailed explanations: E0554, E0557.
[INFO] [stderr] For more information about an error, try `rustc --explain E0554`.
[INFO] [stderr] error: Could not compile `rust_os`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "186467f45cfa3867d53ffd7a2545f0685ebf9c5fe41a4d0ed0c29d14ed0ce53e"`
[INFO] running `"docker" "rm" "-f" "186467f45cfa3867d53ffd7a2545f0685ebf9c5fe41a4d0ed0c29d14ed0ce53e"`
[INFO] [stdout] 186467f45cfa3867d53ffd7a2545f0685ebf9c5fe41a4d0ed0c29d14ed0ce53e