[INFO] updating cached repository FrankYang4/learning-rust
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/FrankYang4/learning-rust
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/FrankYang4/learning-rust" "work/ex/beta-1.38-1/sources/1.37.0/gh/FrankYang4/learning-rust"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/FrankYang4/learning-rust'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/FrankYang4/learning-rust" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/FrankYang4/learning-rust"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/FrankYang4/learning-rust'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 17008ef4e40720b3cc35879685621cb06d8b553b
[INFO] sha for GitHub repo FrankYang4/learning-rust: 17008ef4e40720b3cc35879685621cb06d8b553b
[INFO] validating manifest of FrankYang4/learning-rust 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 FrankYang4/learning-rust 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 FrankYang4/learning-rust
[INFO] finished frobbing FrankYang4/learning-rust
[INFO] frobbed toml for FrankYang4/learning-rust written to work/ex/beta-1.38-1/sources/1.37.0/gh/FrankYang4/learning-rust/Cargo.toml
[INFO] started frobbing FrankYang4/learning-rust
[INFO] finished frobbing FrankYang4/learning-rust
[INFO] frobbed toml for FrankYang4/learning-rust written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/FrankYang4/learning-rust/Cargo.toml
[INFO] crate FrankYang4/learning-rust 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 FrankYang4/learning-rust 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-3/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/FrankYang4/learning-rust:/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] ce19b1562aea15a15b49115504e66ff091c6f8905765498b73747e163db4841a
[INFO] running `"docker" "start" "-a" "ce19b1562aea15a15b49115504e66ff091c6f8905765498b73747e163db4841a"`
[INFO] [stderr]    Compiling learning_rust v0.1.0 (/opt/crater/workdir)
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.37s
[INFO] running `"docker" "inspect" "ce19b1562aea15a15b49115504e66ff091c6f8905765498b73747e163db4841a"`
[INFO] running `"docker" "rm" "-f" "ce19b1562aea15a15b49115504e66ff091c6f8905765498b73747e163db4841a"`
[INFO] [stdout] ce19b1562aea15a15b49115504e66ff091c6f8905765498b73747e163db4841a
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.38-1/worker-3/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/FrankYang4/learning-rust:/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" "test" "--frozen" "--no-run"`
[INFO] [stdout] dbe6844e169a3057e7788310a71cf586ea1c7ee74b8561a46ad346c9a62b607e
[INFO] running `"docker" "start" "-a" "dbe6844e169a3057e7788310a71cf586ea1c7ee74b8561a46ad346c9a62b607e"`
[INFO] [stderr]    Compiling learning_rust v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stderr]  --> examples/boxes.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(box_syntax, box_patterns)]
[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 `learning_rust`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> examples/vec.rs:23:13
[INFO] [stderr]    |
[INFO] [stderr] 23 |         let mut v5 = &mut v4;
[INFO] [stderr]    |             ----^^
[INFO] [stderr]    |             |
[INFO] [stderr]    |             help: remove this `mut`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stderr] 
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "dbe6844e169a3057e7788310a71cf586ea1c7ee74b8561a46ad346c9a62b607e"`
[INFO] running `"docker" "rm" "-f" "dbe6844e169a3057e7788310a71cf586ea1c7ee74b8561a46ad346c9a62b607e"`
[INFO] [stdout] dbe6844e169a3057e7788310a71cf586ea1c7ee74b8561a46ad346c9a62b607e