[INFO] updating cached repository mopp/Axel
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/mopp/Axel
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/mopp/Axel" "work/ex/beta-1.38-1/sources/1.37.0/gh/mopp/Axel"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/mopp/Axel'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/mopp/Axel" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/mopp/Axel"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/mopp/Axel'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 737d5a1dd1a3764ee29968a65abaf4f20da89174
[INFO] sha for GitHub repo mopp/Axel: 737d5a1dd1a3764ee29968a65abaf4f20da89174
[INFO] validating manifest of mopp/Axel 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 mopp/Axel 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 mopp/Axel
[INFO] finished frobbing mopp/Axel
[INFO] frobbed toml for mopp/Axel written to work/ex/beta-1.38-1/sources/1.37.0/gh/mopp/Axel/Cargo.toml
[INFO] started frobbing mopp/Axel
[INFO] finished frobbing mopp/Axel
[INFO] frobbed toml for mopp/Axel written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/mopp/Axel/Cargo.toml
[INFO] crate mopp/Axel 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 mopp/Axel 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/mopp/Axel:/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] b2d95d30cbe12d5076e423fae4e7b32149aba3c845860eccb00a8a7521be180c
[INFO] running `"docker" "start" "-a" "b2d95d30cbe12d5076e423fae4e7b32149aba3c845860eccb00a8a7521be180c"`
[INFO] [stderr]    Compiling bitflags v1.0.3
[INFO] [stderr]    Compiling spin v0.4.9
[INFO] [stderr]    Compiling rlibc v1.0.0
[INFO] [stderr]    Compiling multiboot2 v0.5.0 (https://github.com/phil-opp/multiboot2-elf64.git#784cfb52)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stderr]  --> /opt/crater/cargo-home/registry/src/github.com-1ecc6299db9ec823/spin-0.4.9/src/lib.rs:6:35
[INFO] [stderr]   |
[INFO] [stderr] 6 | #![cfg_attr(feature = "const_fn", feature(const_fn))]
[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 `spin`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "b2d95d30cbe12d5076e423fae4e7b32149aba3c845860eccb00a8a7521be180c"`
[INFO] running `"docker" "rm" "-f" "b2d95d30cbe12d5076e423fae4e7b32149aba3c845860eccb00a8a7521be180c"`
[INFO] [stdout] b2d95d30cbe12d5076e423fae4e7b32149aba3c845860eccb00a8a7521be180c