[INFO] updating cached repository Byron/rust-tracer
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/Byron/rust-tracer
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/Byron/rust-tracer" "work/ex/beta-1.37-6/sources/1.36.0/gh/Byron/rust-tracer"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.37-6/sources/1.36.0/gh/Byron/rust-tracer'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/Byron/rust-tracer" "work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/Byron/rust-tracer"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/Byron/rust-tracer'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] f16522fbd01fb1361ac4b94746e3d46539a54355
[INFO] sha for GitHub repo Byron/rust-tracer: f16522fbd01fb1361ac4b94746e3d46539a54355
[INFO] validating manifest of Byron/rust-tracer 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 Byron/rust-tracer 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 Byron/rust-tracer
[INFO] finished frobbing Byron/rust-tracer
[INFO] frobbed toml for Byron/rust-tracer written to work/ex/beta-1.37-6/sources/1.36.0/gh/Byron/rust-tracer/Cargo.toml
[INFO] started frobbing Byron/rust-tracer
[INFO] finished frobbing Byron/rust-tracer
[INFO] frobbed toml for Byron/rust-tracer written to work/ex/beta-1.37-6/sources/beta-2019-07-23/gh/Byron/rust-tracer/Cargo.toml
[INFO] crate Byron/rust-tracer 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] [stderr] error: the lock file /mnt/big/crater/work/ex/beta-1.37-6/sources/1.36.0/gh/Byron/rust-tracer/Cargo.lock needs to be updated but --locked was passed to prevent this
[INFO] the lockfile is outdated, regenerating it
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.36.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-07-23" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[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 Byron/rust-tracer 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-4/1.36.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/1.36.0/gh/Byron/rust-tracer:/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] b5078d1a723bfaa23526830b4fd097422279e98d3dbcb0871e548c8f874c6fea
[INFO] running `"docker" "start" "-a" "b5078d1a723bfaa23526830b4fd097422279e98d3dbcb0871e548c8f874c6fea"`
[INFO] [stderr]    Compiling threadpool v1.7.1
[INFO] [stderr]    Compiling rtrace v1.0.0 (/opt/crater/workdir)
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 5.13s
[INFO] running `"docker" "inspect" "b5078d1a723bfaa23526830b4fd097422279e98d3dbcb0871e548c8f874c6fea"`
[INFO] running `"docker" "rm" "-f" "b5078d1a723bfaa23526830b4fd097422279e98d3dbcb0871e548c8f874c6fea"`
[INFO] [stdout] b5078d1a723bfaa23526830b4fd097422279e98d3dbcb0871e548c8f874c6fea
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.37-6/worker-4/1.36.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.37-6/sources/1.36.0/gh/Byron/rust-tracer:/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] e241e97eb70efc6d3039a6a16a9b3a046100a8f1acb39659fc2b076d659d7a79
[INFO] running `"docker" "start" "-a" "e241e97eb70efc6d3039a6a16a9b3a046100a8f1acb39659fc2b076d659d7a79"`
[INFO] [stderr]     Blocking waiting for file lock on package cache lock
[INFO] [stderr]    Compiling rtrace v1.0.0 (/opt/crater/workdir)
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]  --> src/rust/lib.rs:1:19
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![cfg_attr(test, feature(test))]
[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 `rtrace`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "e241e97eb70efc6d3039a6a16a9b3a046100a8f1acb39659fc2b076d659d7a79"`
[INFO] running `"docker" "rm" "-f" "e241e97eb70efc6d3039a6a16a9b3a046100a8f1acb39659fc2b076d659d7a79"`
[INFO] [stdout] e241e97eb70efc6d3039a6a16a9b3a046100a8f1acb39659fc2b076d659d7a79