[INFO] crate prometheus_exporter_base 0.5.0 is already in cache
[INFO] testing prometheus_exporter_base-0.5.0 against 1.38.0 for beta-1.39-1
[INFO] extracting crate prometheus_exporter_base 0.5.0 into work/builds/worker-4/source
[INFO] validating manifest of crates.io crate prometheus_exporter_base 0.5.0 on toolchain 1.38.0
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking crates.io crate prometheus_exporter_base 0.5.0
[INFO] finished tweaking crates.io crate prometheus_exporter_base 0.5.0
[INFO] tweaked toml for crates.io crate prometheus_exporter_base 0.5.0 written to work/builds/worker-4/source/Cargo.toml
[INFO] crate crates.io crate prometheus_exporter_base 0.5.0 already has a lockfile, it will not be regenerated
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"docker" "create" "-v" "/big/crater/work/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/big/crater/work/builds/worker-4/source:/opt/rustwide/workdir:ro,Z" "-v" "/big/crater/work/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/big/crater/work/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--network" "none" "rustops/crates-build-env" "/opt/rustwide/cargo-home/bin/cargo" "+1.38.0" "build" "--frozen"`
[INFO] [stdout] ef3216b0f608be33b5adce3c5c022e61d248634792ef5516570c3ff6e3efb6a9
[INFO] running `"docker" "start" "-a" "ef3216b0f608be33b5adce3c5c022e61d248634792ef5516570c3ff6e3efb6a9"`
[INFO] [stderr]    Compiling untrusted v0.7.0
[INFO] [stderr]    Compiling futures-core-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling spin v0.5.1
[INFO] [stderr]    Compiling num-bigint v0.2.2
[INFO] [stderr]    Compiling futures-io-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling serde v1.0.99
[INFO] [stderr]    Compiling num-traits v0.2.8
[INFO] [stderr]    Compiling ring v0.16.7
[INFO] [stderr]    Compiling num-integer v0.1.41
[INFO] [stderr]    Compiling num-complex v0.2.3
[INFO] [stderr]    Compiling num-iter v0.1.39
[INFO] [stderr]    Compiling num-rational v0.2.2
[INFO] [stderr]    Compiling humantime v1.2.0
[INFO] [stderr]    Compiling arrayvec v0.4.11
[INFO] [stderr]    Compiling want v0.2.0
[INFO] [stderr]    Compiling hyper v0.12.33
[INFO] [stderr]    Compiling bytes v0.4.12
[INFO] [stderr]    Compiling futures-cpupool v0.1.8
[INFO] [stderr]    Compiling failure v0.1.5
[INFO] [stderr]    Compiling futures-sink-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling env_logger v0.6.2
[INFO] [stderr]    Compiling futures-channel-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling crossbeam-epoch v0.7.2
[INFO] [stderr]    Compiling tokio-io v0.1.12
[INFO] [stderr]    Compiling tokio-buf v0.1.1
[INFO] [stderr]    Compiling string v0.2.1
[INFO] [stderr]    Compiling http v0.1.18
[INFO] [stderr]    Compiling futures-util-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling crossbeam-deque v0.7.1
[INFO] [stderr]    Compiling tokio-threadpool v0.1.15
[INFO] [stderr]    Compiling tokio-reactor v0.1.9
[INFO] [stderr]    Compiling tokio-tcp v0.1.3
[INFO] [stderr]    Compiling tokio v0.1.22
[INFO] [stderr]    Compiling h2 v0.1.26
[INFO] [stderr]    Compiling http-body v0.1.0
[INFO] [stderr]    Compiling futures-executor-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling num v0.2.0
[INFO] [stderr]    Compiling sct v0.6.0
[INFO] [stderr]    Compiling webpki v0.21.0
[INFO] [stderr]    Compiling futures-preview v0.3.0-alpha.18
[INFO] [stderr]    Compiling ct-logs v0.6.0
[INFO] [stderr]    Compiling rustls v0.16.0
[INFO] [stderr]    Compiling webpki-roots v0.17.0
[INFO] [stderr]    Compiling tokio-rustls v0.10.0
[INFO] [stderr]    Compiling serde_json v1.0.40
[INFO] [stderr]    Compiling hyper-rustls v0.17.0
[INFO] [stderr]    Compiling prometheus_exporter_base v0.5.0 (/opt/rustwide/workdir)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stderr]  --> src/lib.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(async_await)]
[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 `prometheus_exporter_base`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "ef3216b0f608be33b5adce3c5c022e61d248634792ef5516570c3ff6e3efb6a9"`
[INFO] running `"docker" "rm" "-f" "ef3216b0f608be33b5adce3c5c022e61d248634792ef5516570c3ff6e3efb6a9"`
[INFO] [stdout] ef3216b0f608be33b5adce3c5c022e61d248634792ef5516570c3ff6e3efb6a9