[INFO] updating cached repository AleVul/kernel_playground
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/AleVul/kernel_playground
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/AleVul/kernel_playground" "work/ex/beta-1.38-1/sources/1.37.0/gh/AleVul/kernel_playground"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/AleVul/kernel_playground'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/AleVul/kernel_playground" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/AleVul/kernel_playground"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/AleVul/kernel_playground'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] f2027c0a818473d324ee67f318f2235c5d7b7ab1
[INFO] sha for GitHub repo AleVul/kernel_playground: f2027c0a818473d324ee67f318f2235c5d7b7ab1
[INFO] validating manifest of AleVul/kernel_playground 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 AleVul/kernel_playground 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 AleVul/kernel_playground
[INFO] finished frobbing AleVul/kernel_playground
[INFO] frobbed toml for AleVul/kernel_playground written to work/ex/beta-1.38-1/sources/1.37.0/gh/AleVul/kernel_playground/Cargo.toml
[INFO] started frobbing AleVul/kernel_playground
[INFO] finished frobbing AleVul/kernel_playground
[INFO] frobbed toml for AleVul/kernel_playground written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/AleVul/kernel_playground/Cargo.toml
[INFO] crate AleVul/kernel_playground 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 AleVul/kernel_playground 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/gh/AleVul/kernel_playground:/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] fa691ee2a07f154939ea72479d1aec52a2f16bf02fb2dfe6a533888573dd5580
[INFO] running `"docker" "start" "-a" "fa691ee2a07f154939ea72479d1aec52a2f16bf02fb2dfe6a533888573dd5580"`
[INFO] [stderr]    Compiling bitflags v1.0.4
[INFO] [stderr]    Compiling usize_conversions v0.2.0
[INFO] [stderr]    Compiling bit_field v0.9.0
[INFO] [stderr]    Compiling ux v0.1.2
[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/usize_conversions-0.2.0/src/lib.rs:6:1
[INFO] [stderr]   |
[INFO] [stderr] 6 | #![feature(i128_type)]
[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 `usize_conversions`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "fa691ee2a07f154939ea72479d1aec52a2f16bf02fb2dfe6a533888573dd5580"`
[INFO] running `"docker" "rm" "-f" "fa691ee2a07f154939ea72479d1aec52a2f16bf02fb2dfe6a533888573dd5580"`
[INFO] [stdout] fa691ee2a07f154939ea72479d1aec52a2f16bf02fb2dfe6a533888573dd5580