[INFO] crate sarek 0.1.0 is already in cache
[INFO] extracting crate sarek 0.1.0 into work/ex/beta-1.38-1/sources/1.37.0/reg/sarek/0.1.0
[INFO] extracting crate sarek 0.1.0 into work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/sarek/0.1.0
[INFO] validating manifest of sarek-0.1.0 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 sarek-0.1.0 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 sarek-0.1.0
[INFO] finished frobbing sarek-0.1.0
[INFO] frobbed toml for sarek-0.1.0 written to work/ex/beta-1.38-1/sources/1.37.0/reg/sarek/0.1.0/Cargo.toml
[INFO] started frobbing sarek-0.1.0
[INFO] finished frobbing sarek-0.1.0
[INFO] frobbed toml for sarek-0.1.0 written to work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/sarek/0.1.0/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 sarek-0.1.0 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-5/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/reg/sarek/0.1.0:/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] 1065c46c1551f5a8c5276bfd676274bc8672353efb0bb3c7914162630aa3fe12
[INFO] running `"docker" "start" "-a" "1065c46c1551f5a8c5276bfd676274bc8672353efb0bb3c7914162630aa3fe12"`
[INFO] [stderr]    Compiling proc-macro2 v0.4.30
[INFO] [stderr]    Compiling autocfg v0.1.6
[INFO] [stderr]    Compiling proc-macro2 v1.0.1
[INFO] [stderr]    Compiling semver-parser v0.7.0
[INFO] [stderr]    Compiling syn v0.15.44
[INFO] [stderr]    Compiling unicode-xid v0.2.0
[INFO] [stderr]    Compiling syn v1.0.3
[INFO] [stderr]    Compiling proc-macro-hack-impl v0.4.2
[INFO] [stderr]    Compiling stable_deref_trait v1.1.1
[INFO] [stderr]    Compiling serde v1.0.99
[INFO] [stderr]    Compiling scopeguard v0.3.3
[INFO] [stderr]    Compiling smallvec v0.6.10
[INFO] [stderr]    Compiling spin v0.4.10
[INFO] [stderr]    Compiling rand_core v0.3.1
[INFO] [stderr]    Compiling rand_jitter v0.1.4
[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/spin-0.4.10/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" "1065c46c1551f5a8c5276bfd676274bc8672353efb0bb3c7914162630aa3fe12"`
[INFO] running `"docker" "rm" "-f" "1065c46c1551f5a8c5276bfd676274bc8672353efb0bb3c7914162630aa3fe12"`
[INFO] [stdout] 1065c46c1551f5a8c5276bfd676274bc8672353efb0bb3c7914162630aa3fe12