[INFO] updating cached repository mlsteele/bittles
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/mlsteele/bittles
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/mlsteele/bittles" "work/ex/beta-1.37-6/sources/1.36.0/gh/mlsteele/bittles"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.37-6/sources/1.36.0/gh/mlsteele/bittles'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/mlsteele/bittles" "work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/mlsteele/bittles"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/mlsteele/bittles'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 68441273c2e5aaa5e7e19d35c2b8fdeee0ac92af
[INFO] sha for GitHub repo mlsteele/bittles: 68441273c2e5aaa5e7e19d35c2b8fdeee0ac92af
[INFO] validating manifest of mlsteele/bittles on toolchain 1.36.0
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of mlsteele/bittles on toolchain beta-2019-07-23
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing mlsteele/bittles
[INFO] finished frobbing mlsteele/bittles
[INFO] frobbed toml for mlsteele/bittles written to work/ex/beta-1.37-6/sources/1.36.0/gh/mlsteele/bittles/Cargo.toml
[INFO] started frobbing mlsteele/bittles
[INFO] finished frobbing mlsteele/bittles
[INFO] frobbed toml for mlsteele/bittles written to work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/mlsteele/bittles/Cargo.toml
[INFO] crate mlsteele/bittles already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] testing mlsteele/bittles against beta-2019-07-23 for beta-1.37-6
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.37-6/worker-7/beta-2019-07-23:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/mlsteele/bittles:/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" "+beta-2019-07-23" "build" "--frozen"`
[INFO] [stdout] 7cdb29227ed3977713ac637733d2f81e6d9bb1e1485c65225846d77b0b57cd6e
[INFO] running `"docker" "start" "-a" "7cdb29227ed3977713ac637733d2f81e6d9bb1e1485c65225846d77b0b57cd6e"`
[INFO] [stderr]    Compiling rayon-core v1.0.0
[INFO] [stderr]    Compiling futures v0.1.13
[INFO] [stderr]    Compiling slog v2.0.5
[INFO] [stderr]    Compiling httparse v1.2.2
[INFO] [stderr]    Compiling isatty v0.1.3
[INFO] [stderr]    Compiling backtrace-sys v0.1.10
[INFO] [stderr]    Compiling serde_cbor v0.5.2
[INFO] [stderr]    Compiling bytes v0.4.3
[INFO] [stderr]    Compiling aho-corasick v0.6.3
[INFO] [stderr] error[E0446]: private type `NeverStruct` in public interface
[INFO] [stderr]     --> /opt/crater/cargo-home/registry/src/github.com-1ecc6299db9ec823/slog-2.0.5/src/lib.rs:1180:5
[INFO] [stderr]      |
[INFO] [stderr] 1180 |     type Err = Never;
[INFO] [stderr]      |     ^^^^^^^^^^^^^^^^^ can't leak private type
[INFO] [stderr] ...
[INFO] [stderr] 2868 | struct NeverStruct(());
[INFO] [stderr]      | - `NeverStruct` declared as private
[INFO] [stderr] 
[INFO] [stderr] error[E0446]: private type `NeverStruct` in public interface
[INFO] [stderr]     --> /opt/crater/cargo-home/registry/src/github.com-1ecc6299db9ec823/slog-2.0.5/src/lib.rs:1465:5
[INFO] [stderr]      |
[INFO] [stderr] 1465 |     type Err = Never;
[INFO] [stderr]      |     ^^^^^^^^^^^^^^^^^ can't leak private type
[INFO] [stderr] ...
[INFO] [stderr] 2868 | struct NeverStruct(());
[INFO] [stderr]      | - `NeverStruct` declared as private
[INFO] [stderr] 
[INFO] [stderr] error[E0446]: private type `NeverStruct` in public interface
[INFO] [stderr]     --> /opt/crater/cargo-home/registry/src/github.com-1ecc6299db9ec823/slog-2.0.5/src/lib.rs:1630:5
[INFO] [stderr]      |
[INFO] [stderr] 1630 |     type Err = Never;
[INFO] [stderr]      |     ^^^^^^^^^^^^^^^^^ can't leak private type
[INFO] [stderr] ...
[INFO] [stderr] 2868 | struct NeverStruct(());
[INFO] [stderr]      | - `NeverStruct` declared as private
[INFO] [stderr] 
[INFO] [stderr] error[E0446]: private type `NeverStruct` in public interface
[INFO] [stderr]     --> /opt/crater/cargo-home/registry/src/github.com-1ecc6299db9ec823/slog-2.0.5/src/lib.rs:1662:5
[INFO] [stderr]      |
[INFO] [stderr] 1662 |     type Err = Never;
[INFO] [stderr]      |     ^^^^^^^^^^^^^^^^^ can't leak private type
[INFO] [stderr] ...
[INFO] [stderr] 2868 | struct NeverStruct(());
[INFO] [stderr]      | - `NeverStruct` declared as private
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 4 previous errors
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0446`.
[INFO] [stderr] error: Could not compile `slog`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "7cdb29227ed3977713ac637733d2f81e6d9bb1e1485c65225846d77b0b57cd6e"`
[INFO] running `"docker" "rm" "-f" "7cdb29227ed3977713ac637733d2f81e6d9bb1e1485c65225846d77b0b57cd6e"`
[INFO] [stdout] 7cdb29227ed3977713ac637733d2f81e6d9bb1e1485c65225846d77b0b57cd6e