[INFO] updating cached repository Ibexian/char_predictor
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/Ibexian/char_predictor
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/Ibexian/char_predictor" "work/ex/beta-1.38-1/sources/1.37.0/gh/Ibexian/char_predictor"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/Ibexian/char_predictor'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/Ibexian/char_predictor" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/Ibexian/char_predictor"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/Ibexian/char_predictor'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 4a75007895fc1f57326754287a21332c038fdf0f
[INFO] sha for GitHub repo Ibexian/char_predictor: 4a75007895fc1f57326754287a21332c038fdf0f
[INFO] validating manifest of Ibexian/char_predictor 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 Ibexian/char_predictor 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 Ibexian/char_predictor
[INFO] finished frobbing Ibexian/char_predictor
[INFO] frobbed toml for Ibexian/char_predictor written to work/ex/beta-1.38-1/sources/1.37.0/gh/Ibexian/char_predictor/Cargo.toml
[INFO] started frobbing Ibexian/char_predictor
[INFO] finished frobbing Ibexian/char_predictor
[INFO] frobbed toml for Ibexian/char_predictor written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/Ibexian/char_predictor/Cargo.toml
[INFO] crate Ibexian/char_predictor 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 Ibexian/char_predictor 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/Ibexian/char_predictor:/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] 7bc86938cc273e6823cc291c81479eddd3d9ac8ff2cf369cb43c10da01aa0af8
[INFO] running `"docker" "start" "-a" "7bc86938cc273e6823cc291c81479eddd3d9ac8ff2cf369cb43c10da01aa0af8"`
[INFO] [stderr]    Compiling proc-macro2 v0.4.13
[INFO] [stderr]    Compiling ryu v0.2.5
[INFO] [stderr]    Compiling serde v1.0.74
[INFO] [stderr]    Compiling wasm-bindgen-shared v0.2.17
[INFO] [stderr]    Compiling libz-sys v1.0.20
[INFO] [stderr]    Compiling openssl-sys v0.9.35
[INFO] [stderr]    Compiling curl-sys v0.4.8
[INFO] [stderr]    Compiling miniz-sys v0.1.10
[INFO] [stderr]    Compiling xattr v0.2.2
[INFO] [stderr]    Compiling socket2 v0.3.7
[INFO] [stderr]    Compiling num-complex v0.1.43
[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/proc-macro2-0.4.13/src/lib.rs:49:5
[INFO] [stderr]    |
[INFO] [stderr] 49 |     feature(proc_macro_raw_ident, proc_macro_span)
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr]    Compiling aligned_alloc v0.1.3
[INFO] [stderr] error[E0658]: use of unstable library feature 'proc_macro_def_site'
[INFO] [stderr]    --> /opt/crater/cargo-home/registry/src/github.com-1ecc6299db9ec823/proc-macro2-0.4.13/src/unstable.rs:359:27
[INFO] [stderr]     |
[INFO] [stderr] 359 |             Span::Nightly(proc_macro::Span::def_site())
[INFO] [stderr]     |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: for more information, see https://github.com/rust-lang/rust/issues/54724
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 2 previous errors
[INFO] [stderr] 
[INFO] [stderr] Some errors have detailed explanations: E0554, E0658.
[INFO] [stderr] For more information about an error, try `rustc --explain E0554`.
[INFO] [stderr] error: Could not compile `proc-macro2`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "7bc86938cc273e6823cc291c81479eddd3d9ac8ff2cf369cb43c10da01aa0af8"`
[INFO] running `"docker" "rm" "-f" "7bc86938cc273e6823cc291c81479eddd3d9ac8ff2cf369cb43c10da01aa0af8"`
[INFO] [stdout] 7bc86938cc273e6823cc291c81479eddd3d9ac8ff2cf369cb43c10da01aa0af8