[INFO] updating cached repository xanahopper/leetcode
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/xanahopper/leetcode
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/xanahopper/leetcode" "work/ex/beta-1.38-1/sources/1.37.0/gh/xanahopper/leetcode"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/xanahopper/leetcode'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/xanahopper/leetcode" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/xanahopper/leetcode"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/xanahopper/leetcode'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] fd0e2635ac291b60564ef5ebab5aedefe9749dec
[INFO] sha for GitHub repo xanahopper/leetcode: fd0e2635ac291b60564ef5ebab5aedefe9749dec
[INFO] validating manifest of xanahopper/leetcode 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 xanahopper/leetcode 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 xanahopper/leetcode
[INFO] finished frobbing xanahopper/leetcode
[INFO] frobbed toml for xanahopper/leetcode written to work/ex/beta-1.38-1/sources/1.37.0/gh/xanahopper/leetcode/Cargo.toml
[INFO] started frobbing xanahopper/leetcode
[INFO] finished frobbing xanahopper/leetcode
[INFO] frobbed toml for xanahopper/leetcode written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/xanahopper/leetcode/Cargo.toml
[INFO] crate xanahopper/leetcode 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 xanahopper/leetcode 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-4/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/gh/xanahopper/leetcode:/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] ce2e121ef916792ef7f5c0860471d8ec7e4456dc789c0ab1029fb8c7233197ca
[INFO] running `"docker" "start" "-a" "ce2e121ef916792ef7f5c0860471d8ec7e4456dc789c0ab1029fb8c7233197ca"`
[INFO] [stderr]    Compiling serde_json v1.0.39
[INFO] [stderr]    Compiling leetcode_test v0.1.1
[INFO] [stderr]    Compiling leetcode_prelude 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/leetcode_prelude-0.1.2/src/lib.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(uniform_paths)]
[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 `leetcode_prelude`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "ce2e121ef916792ef7f5c0860471d8ec7e4456dc789c0ab1029fb8c7233197ca"`
[INFO] running `"docker" "rm" "-f" "ce2e121ef916792ef7f5c0860471d8ec7e4456dc789c0ab1029fb8c7233197ca"`
[INFO] [stdout] ce2e121ef916792ef7f5c0860471d8ec7e4456dc789c0ab1029fb8c7233197ca