[INFO] crate aljabar 0.2.7 is already in cache
[INFO] extracting crate aljabar 0.2.7 into work/ex/beta-1.38-1/sources/1.37.0/reg/aljabar/0.2.7
[INFO] extracting crate aljabar 0.2.7 into work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/aljabar/0.2.7
[INFO] validating manifest of aljabar-0.2.7 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 aljabar-0.2.7 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 aljabar-0.2.7
[INFO] finished frobbing aljabar-0.2.7
[INFO] frobbed toml for aljabar-0.2.7 written to work/ex/beta-1.38-1/sources/1.37.0/reg/aljabar/0.2.7/Cargo.toml
[INFO] started frobbing aljabar-0.2.7
[INFO] finished frobbing aljabar-0.2.7
[INFO] frobbed toml for aljabar-0.2.7 written to work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/aljabar/0.2.7/Cargo.toml
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[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 aljabar-0.2.7 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-7/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/reg/aljabar/0.2.7:/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] 7e5f8767bae8ed9987ed00307fe320c48eb683224983ac536dc1589b8875425b
[INFO] running `"docker" "start" "-a" "7e5f8767bae8ed9987ed00307fe320c48eb683224983ac536dc1589b8875425b"`
[INFO] [stderr]    Compiling aljabar v0.2.7 (/opt/crater/workdir)
[INFO] [stderr] warning: the feature `const_generics` is incomplete and may cause the compiler to crash
[INFO] [stderr]   --> src/lib.rs:31:12
[INFO] [stderr]    |
[INFO] [stderr] 31 | #![feature(const_generics)]
[INFO] [stderr]    |            ^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]   --> src/lib.rs:31:1
[INFO] [stderr]    |
[INFO] [stderr] 31 | #![feature(const_generics)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]   --> src/lib.rs:32:1
[INFO] [stderr]    |
[INFO] [stderr] 32 | #![feature(trivial_bounds)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]   --> src/lib.rs:33:1
[INFO] [stderr]    |
[INFO] [stderr] 33 | #![feature(specialization)]
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 3 previous errors
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0554`.
[INFO] [stderr] error: Could not compile `aljabar`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "7e5f8767bae8ed9987ed00307fe320c48eb683224983ac536dc1589b8875425b"`
[INFO] running `"docker" "rm" "-f" "7e5f8767bae8ed9987ed00307fe320c48eb683224983ac536dc1589b8875425b"`
[INFO] [stdout] 7e5f8767bae8ed9987ed00307fe320c48eb683224983ac536dc1589b8875425b