[INFO] updating cached repository jrheard/rustbook
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/jrheard/rustbook
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/jrheard/rustbook" "work/ex/beta-1.38-1/sources/1.37.0/gh/jrheard/rustbook"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/jrheard/rustbook'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/jrheard/rustbook" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/jrheard/rustbook"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/jrheard/rustbook'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 751299e1df274231b14a0687fbe79103b6090fcc
[INFO] sha for GitHub repo jrheard/rustbook: 751299e1df274231b14a0687fbe79103b6090fcc
[INFO] validating manifest of jrheard/rustbook 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 jrheard/rustbook 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 jrheard/rustbook
[INFO] finished frobbing jrheard/rustbook
[INFO] frobbed toml for jrheard/rustbook written to work/ex/beta-1.38-1/sources/1.37.0/gh/jrheard/rustbook/Cargo.toml
[INFO] started frobbing jrheard/rustbook
[INFO] finished frobbing jrheard/rustbook
[INFO] frobbed toml for jrheard/rustbook written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/jrheard/rustbook/Cargo.toml
[INFO] crate jrheard/rustbook 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] [stderr]     Blocking waiting for file lock on package cache
[INFO] testing jrheard/rustbook against beta-2019-08-13 for beta-1.38-1
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.38-1/worker-2/beta-2019-08-13:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/jrheard/rustbook:/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-2019-08-13" "build" "--frozen"`
[INFO] [stdout] c90d92df951217462720de1f81f08c205a954d9c72847431a7a2483129a928ab
[INFO] running `"docker" "start" "-a" "c90d92df951217462720de1f81f08c205a954d9c72847431a7a2483129a928ab"`
[INFO] [stderr]    Compiling assert_approx_eq v1.1.0
[INFO] [stderr]    Compiling chapter_8_exercises v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] warning: unused import: `assert_approx_eq::assert_approx_eq`
[INFO] [stderr]  --> src/main.rs:5:5
[INFO] [stderr]   |
[INFO] [stderr] 5 | use assert_approx_eq::assert_approx_eq;
[INFO] [stderr]   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stderr] 
[INFO] [stderr] error[E0601]: `main` function not found in crate `chapter_8_exercises`
[INFO] [stderr]   |
[INFO] [stderr]   = note: consider adding a `main` function to `src/main.rs`
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0601`.
[INFO] [stderr] error: Could not compile `chapter_8_exercises`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "c90d92df951217462720de1f81f08c205a954d9c72847431a7a2483129a928ab"`
[INFO] running `"docker" "rm" "-f" "c90d92df951217462720de1f81f08c205a954d9c72847431a7a2483129a928ab"`
[INFO] [stdout] c90d92df951217462720de1f81f08c205a954d9c72847431a7a2483129a928ab