[INFO] fetching crate const-alg 0.1.1...
[INFO] extracting crate const-alg 0.1.1 into work/ex/beta-1.37-6/sources/1.36.0/reg/const-alg/0.1.1
[INFO] extracting crate const-alg 0.1.1 into work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/const-alg/0.1.1
[INFO] validating manifest of const-alg-0.1.1 on toolchain 1.36.0
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of const-alg-0.1.1 on toolchain beta-2019-07-23
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing const-alg-0.1.1
[INFO] finished frobbing const-alg-0.1.1
[INFO] frobbed toml for const-alg-0.1.1 written to work/ex/beta-1.37-6/sources/1.36.0/reg/const-alg/0.1.1/Cargo.toml
[INFO] started frobbing const-alg-0.1.1
[INFO] finished frobbing const-alg-0.1.1
[INFO] frobbed toml for const-alg-0.1.1 written to work/ex/beta-1.37-6/sources/beta-2019-07-23/reg/const-alg/0.1.1/Cargo.toml
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] [stderr]     Blocking waiting for file lock on package cache lock
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr]     Blocking waiting for file lock on package cache lock
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded array-vec v0.1.3
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing const-alg-0.1.1 against 1.36.0 for beta-1.37-6
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.37-6/worker-6/1.36.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/1.36.0/reg/const-alg/0.1.1:/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" "+1.36.0" "build" "--frozen"`
[INFO] [stdout] 3c9d8e6cddc47bdc453b699da0773ff43e17c7f35cf7ad9cb95c9cc5b03fadfd
[INFO] running `"docker" "start" "-a" "3c9d8e6cddc47bdc453b699da0773ff43e17c7f35cf7ad9cb95c9cc5b03fadfd"`
[INFO] [stderr]    Compiling array-vec v0.1.3
[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/array-vec-0.1.3/src/lib.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(const_generics, specialization, maybe_uninit_extra, maybe_uninit_slice)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error[E0658]: use of unstable library feature 'iter_nth_back'
[INFO] [stderr]    --> /opt/crater/cargo-home/registry/src/github.com-1ecc6299db9ec823/array-vec-0.1.3/src/lib.rs:337:5
[INFO] [stderr]     |
[INFO] [stderr] 337 | /     fn nth_back(&mut self, n: usize) -> Option<T> {
[INFO] [stderr] 338 | |         match self.arr.len.checked_sub(n) {
[INFO] [stderr] 339 | |             Some(len) if self.idx < len => {
[INFO] [stderr] 340 | |                 unsafe {
[INFO] [stderr] ...   |
[INFO] [stderr] 353 | |         }
[INFO] [stderr] 354 | |     }
[INFO] [stderr]     | |_____^
[INFO] [stderr]     |
[INFO] [stderr]     = note: for more information, see https://github.com/rust-lang/rust/issues/56995
[INFO] [stderr] 
[INFO] [stderr] error[E0119]: conflicting implementations of trait `std::convert::TryInto<[type error]>` for type `ArrayVec<_, _>`:
[INFO] [stderr]    --> /opt/crater/cargo-home/registry/src/github.com-1ecc6299db9ec823/array-vec-0.1.3/src/lib.rs:223:1
[INFO] [stderr]     |
[INFO] [stderr] 223 | impl<T, const N: usize> TryInto<[T; N]> for ArrayVec<T, { N }> {
[INFO] [stderr]     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: conflicting implementation in crate `core`:
[INFO] [stderr]             - impl<T, U> std::convert::TryInto<U> for T
[INFO] [stderr]               where U: std::convert::TryFrom<T>;
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 3 previous errors
[INFO] [stderr] 
[INFO] [stderr] Some errors have detailed explanations: E0119, E0554, E0658.
[INFO] [stderr] For more information about an error, try `rustc --explain E0119`.
[INFO] [stderr] error: Could not compile `array-vec`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "3c9d8e6cddc47bdc453b699da0773ff43e17c7f35cf7ad9cb95c9cc5b03fadfd"`
[INFO] running `"docker" "rm" "-f" "3c9d8e6cddc47bdc453b699da0773ff43e17c7f35cf7ad9cb95c9cc5b03fadfd"`
[INFO] [stdout] 3c9d8e6cddc47bdc453b699da0773ff43e17c7f35cf7ad9cb95c9cc5b03fadfd