[INFO] crate prongs 0.0.4 is already in cache
[INFO] extracting crate prongs 0.0.4 into work/ex/beta-1.38-1/sources/1.37.0/reg/prongs/0.0.4
[INFO] extracting crate prongs 0.0.4 into work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/prongs/0.0.4
[INFO] validating manifest of prongs-0.0.4 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 prongs-0.0.4 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 prongs-0.0.4
[INFO] finished frobbing prongs-0.0.4
[INFO] frobbed toml for prongs-0.0.4 written to work/ex/beta-1.38-1/sources/1.37.0/reg/prongs/0.0.4/Cargo.toml
[INFO] started frobbing prongs-0.0.4
[INFO] finished frobbing prongs-0.0.4
[INFO] frobbed toml for prongs-0.0.4 written to work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/prongs/0.0.4/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] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] testing prongs-0.0.4 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-1/beta-2019-08-13:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/prongs/0.0.4:/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] 879f3283b251dd2e795681afbe2f284fbf2d933085e81eae5b2368e035f02131
[INFO] running `"docker" "start" "-a" "879f3283b251dd2e795681afbe2f284fbf2d933085e81eae5b2368e035f02131"`
[INFO] [stderr]    Compiling prongs v0.0.4 (/opt/crater/workdir)
[INFO] [stderr] error: No backend selected, use features=<backend> in Cargo.toml or --features <backend> when building directly.
[INFO] [stderr]   --> src/lib.rs:14:1
[INFO] [stderr]    |
[INFO] [stderr] 14 | compile_error!("No backend selected, use features=<backend> in Cargo.toml or --features <backend> when building directly.");
[INFO] [stderr]    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] error: Could not compile `prongs`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "879f3283b251dd2e795681afbe2f284fbf2d933085e81eae5b2368e035f02131"`
[INFO] running `"docker" "rm" "-f" "879f3283b251dd2e795681afbe2f284fbf2d933085e81eae5b2368e035f02131"`
[INFO] [stdout] 879f3283b251dd2e795681afbe2f284fbf2d933085e81eae5b2368e035f02131