[INFO] updating cached repository LooMaclin/concat_const_example
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/LooMaclin/concat_const_example
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/LooMaclin/concat_const_example" "work/ex/beta-1.38-1/sources/1.37.0/gh/LooMaclin/concat_const_example"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/LooMaclin/concat_const_example'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/LooMaclin/concat_const_example" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/LooMaclin/concat_const_example"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/LooMaclin/concat_const_example'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] bdc5902bdcf36109bf683566f15bfa0021882f43
[INFO] sha for GitHub repo LooMaclin/concat_const_example: bdc5902bdcf36109bf683566f15bfa0021882f43
[INFO] validating manifest of LooMaclin/concat_const_example 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 LooMaclin/concat_const_example 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 LooMaclin/concat_const_example
[INFO] finished frobbing LooMaclin/concat_const_example
[INFO] frobbed toml for LooMaclin/concat_const_example written to work/ex/beta-1.38-1/sources/1.37.0/gh/LooMaclin/concat_const_example/Cargo.toml
[INFO] started frobbing LooMaclin/concat_const_example
[INFO] finished frobbing LooMaclin/concat_const_example
[INFO] frobbed toml for LooMaclin/concat_const_example written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/LooMaclin/concat_const_example/Cargo.toml
[INFO] crate LooMaclin/concat_const_example 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 LooMaclin/concat_const_example 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-0/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/LooMaclin/concat_const_example:/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] 1676f0e664e485b6d8ba05928f6207af719528248ca41a81f81e38335f785320
[INFO] running `"docker" "start" "-a" "1676f0e664e485b6d8ba05928f6207af719528248ca41a81f81e38335f785320"`
[INFO] [stderr]    Compiling const-concat v0.1.1 (https://github.com/Candunc/const-concat?branch=patch-1#7fbd831e)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stderr]   --> /opt/crater/cargo-home/git/checkouts/const-concat-07bb967c112852f5/7fbd831/src/lib.rs:24:1
[INFO] [stderr]    |
[INFO] [stderr] 24 | #![feature(const_fn, const_fn_union, const_str_as_bytes, const_str_len, untagged_unions)]
[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 `const-concat`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "1676f0e664e485b6d8ba05928f6207af719528248ca41a81f81e38335f785320"`
[INFO] running `"docker" "rm" "-f" "1676f0e664e485b6d8ba05928f6207af719528248ca41a81f81e38335f785320"`
[INFO] [stdout] 1676f0e664e485b6d8ba05928f6207af719528248ca41a81f81e38335f785320