[INFO] crate drone 0.6.0 is already in cache
[INFO] extracting crate drone 0.6.0 into work/ex/beta-1.38-1/sources/1.37.0/reg/drone/0.6.0
[INFO] extracting crate drone 0.6.0 into work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/drone/0.6.0
[INFO] validating manifest of drone-0.6.0 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 drone-0.6.0 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 drone-0.6.0
[INFO] finished frobbing drone-0.6.0
[INFO] frobbed toml for drone-0.6.0 written to work/ex/beta-1.38-1/sources/1.37.0/reg/drone/0.6.0/Cargo.toml
[INFO] started frobbing drone-0.6.0
[INFO] finished frobbing drone-0.6.0
[INFO] frobbed toml for drone-0.6.0 written to work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/drone/0.6.0/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] [stderr]     Blocking waiting for file lock on package cache
[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] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing drone-0.6.0 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-2/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/drone/0.6.0:/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" "+beta-2019-08-13" "build" "--frozen"`
[INFO] [stdout] e5c7ff4174300b7b1d541e08bb6c71c4d1b0f166aa061b6fbafe1aa05a2c861e
[INFO] running `"docker" "start" "-a" "e5c7ff4174300b7b1d541e08bb6c71c4d1b0f166aa061b6fbafe1aa05a2c861e"`
[INFO] [stderr]    Compiling bitflags v1.1.0
[INFO] [stderr]    Compiling futures v0.1.28
[INFO] [stderr]    Compiling drone-macros v0.6.0
[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/drone-macros-0.6.0/src/lib.rs:4:1
[INFO] [stderr]   |
[INFO] [stderr] 4 | #![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 `drone-macros`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "e5c7ff4174300b7b1d541e08bb6c71c4d1b0f166aa061b6fbafe1aa05a2c861e"`
[INFO] running `"docker" "rm" "-f" "e5c7ff4174300b7b1d541e08bb6c71c4d1b0f166aa061b6fbafe1aa05a2c861e"`
[INFO] [stdout] e5c7ff4174300b7b1d541e08bb6c71c4d1b0f166aa061b6fbafe1aa05a2c861e