[INFO] updating cached repository yuhangwang/copy_files-rs
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/yuhangwang/copy_files-rs
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/yuhangwang/copy_files-rs" "work/ex/beta-1.38-1/sources/1.37.0/gh/yuhangwang/copy_files-rs"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/yuhangwang/copy_files-rs'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/yuhangwang/copy_files-rs" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/yuhangwang/copy_files-rs"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/yuhangwang/copy_files-rs'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 28fc7a1e5d719ded63b50fc519cc32df2d7e447e
[INFO] sha for GitHub repo yuhangwang/copy_files-rs: 28fc7a1e5d719ded63b50fc519cc32df2d7e447e
[INFO] validating manifest of yuhangwang/copy_files-rs 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 yuhangwang/copy_files-rs 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 yuhangwang/copy_files-rs
[INFO] finished frobbing yuhangwang/copy_files-rs
[INFO] frobbed toml for yuhangwang/copy_files-rs written to work/ex/beta-1.38-1/sources/1.37.0/gh/yuhangwang/copy_files-rs/Cargo.toml
[INFO] started frobbing yuhangwang/copy_files-rs
[INFO] finished frobbing yuhangwang/copy_files-rs
[INFO] frobbed toml for yuhangwang/copy_files-rs written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/yuhangwang/copy_files-rs/Cargo.toml
[INFO] crate yuhangwang/copy_files-rs 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 yuhangwang/copy_files-rs 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-1/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/gh/yuhangwang/copy_files-rs:/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] 7d37879d040245b81241757f17d68ead73c91e5c3d0ceefee43ae62736d7a2cf
[INFO] running `"docker" "start" "-a" "7d37879d040245b81241757f17d68ead73c91e5c3d0ceefee43ae62736d7a2cf"`
[INFO] [stderr]    Compiling copy_files v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] error[E0658]: use of unstable library feature 'rustc_private': this crate is being loaded from the sysroot, an unstable location; did you mean to load this crate from crates.io via `Cargo.toml` instead?
[INFO] [stderr]  --> src/main.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | extern crate serde_json;
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: for more information, see https://github.com/rust-lang/rust/issues/27812
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0658`.
[INFO] [stderr] error: Could not compile `copy_files`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "7d37879d040245b81241757f17d68ead73c91e5c3d0ceefee43ae62736d7a2cf"`
[INFO] running `"docker" "rm" "-f" "7d37879d040245b81241757f17d68ead73c91e5c3d0ceefee43ae62736d7a2cf"`
[INFO] [stdout] 7d37879d040245b81241757f17d68ead73c91e5c3d0ceefee43ae62736d7a2cf