[INFO] updating cached repository SteamPoweredAnimal/approx
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/SteamPoweredAnimal/approx
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/SteamPoweredAnimal/approx" "work/ex/beta-1.37-6/sources/1.36.0/gh/SteamPoweredAnimal/approx"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.37-6/sources/1.36.0/gh/SteamPoweredAnimal/approx'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/SteamPoweredAnimal/approx" "work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/SteamPoweredAnimal/approx"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/SteamPoweredAnimal/approx'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 04130cb0a6acb1faf2b5204afb1945dd674b38f7
[INFO] sha for GitHub repo SteamPoweredAnimal/approx: 04130cb0a6acb1faf2b5204afb1945dd674b38f7
[INFO] validating manifest of SteamPoweredAnimal/approx 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 SteamPoweredAnimal/approx 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 SteamPoweredAnimal/approx
[INFO] finished frobbing SteamPoweredAnimal/approx
[INFO] frobbed toml for SteamPoweredAnimal/approx written to work/ex/beta-1.37-6/sources/1.36.0/gh/SteamPoweredAnimal/approx/Cargo.toml
[INFO] started frobbing SteamPoweredAnimal/approx
[INFO] finished frobbing SteamPoweredAnimal/approx
[INFO] frobbed toml for SteamPoweredAnimal/approx written to work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/SteamPoweredAnimal/approx/Cargo.toml
[INFO] crate SteamPoweredAnimal/approx already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing SteamPoweredAnimal/approx 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/gh/SteamPoweredAnimal/approx:/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] 3c2fb4f115b52d9292982bc08cdd1f5377bdf029f3f67a548ff506fcfa6e4fac
[INFO] running `"docker" "start" "-a" "3c2fb4f115b52d9292982bc08cdd1f5377bdf029f3f67a548ff506fcfa6e4fac"`
[INFO] [stderr]    Compiling approx v0.1.0 (/opt/crater/workdir)
[INFO] [stderr]    Compiling backtrace-sys v0.1.28
[INFO] [stderr]    Compiling syn v0.15.25
[INFO] [stderr]    Compiling backtrace v0.3.13
[INFO] [stderr]    Compiling synstructure v0.10.1
[INFO] [stderr]    Compiling structopt-derive v0.2.14
[INFO] [stderr]    Compiling failure_derive v0.1.5
[INFO] [stderr]    Compiling structopt v0.2.14
[INFO] [stderr]    Compiling failure v0.1.5
[INFO] [stderr] warning: unused variable: `config`
[INFO] [stderr]  --> src/lib.rs:8:17
[INFO] [stderr]   |
[INFO] [stderr] 8 | pub fn generate(config: Config) -> Result<(), Error> {
[INFO] [stderr]   |                 ^^^^^^ help: consider prefixing with an underscore: `_config`
[INFO] [stderr]   |
[INFO] [stderr]   = note: #[warn(unused_variables)] on by default
[INFO] [stderr] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 26.54s
[INFO] running `"docker" "inspect" "3c2fb4f115b52d9292982bc08cdd1f5377bdf029f3f67a548ff506fcfa6e4fac"`
[INFO] running `"docker" "rm" "-f" "3c2fb4f115b52d9292982bc08cdd1f5377bdf029f3f67a548ff506fcfa6e4fac"`
[INFO] [stdout] 3c2fb4f115b52d9292982bc08cdd1f5377bdf029f3f67a548ff506fcfa6e4fac
[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/gh/SteamPoweredAnimal/approx:/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" "test" "--frozen" "--no-run"`
[INFO] [stdout] 278deeb220e82b8632ddd57577f198b87b126519f7e450f10de2ee56ed094fa4
[INFO] running `"docker" "start" "-a" "278deeb220e82b8632ddd57577f198b87b126519f7e450f10de2ee56ed094fa4"`
[INFO] [stderr]    Compiling test-case-derive v0.2.1
[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/test-case-derive-0.2.1/src/lib.rs:214:1
[INFO] [stderr]     |
[INFO] [stderr] 214 | #![feature(proc_macro)]
[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 `test-case-derive`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "278deeb220e82b8632ddd57577f198b87b126519f7e450f10de2ee56ed094fa4"`
[INFO] running `"docker" "rm" "-f" "278deeb220e82b8632ddd57577f198b87b126519f7e450f10de2ee56ed094fa4"`
[INFO] [stdout] 278deeb220e82b8632ddd57577f198b87b126519f7e450f10de2ee56ed094fa4