[INFO] cloning repository https://github.com/emk/drop-async-examples
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/emk/drop-async-examples" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Femk%2Fdrop-async-examples", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Femk%2Fdrop-async-examples'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 48d2b3609ae85fbba497b5134135ded3fbedbb32
[INFO] testing emk/drop-async-examples against 1.55.0 for beta-1.56-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Femk%2Fdrop-async-examples" "/workspace/builds/worker-0/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-0/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/emk/drop-async-examples on toolchain 1.55.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] removed /workspace/builds/worker-0/source/rust-toolchain
[INFO] started tweaking git repo https://github.com/emk/drop-async-examples
[INFO] finished tweaking git repo https://github.com/emk/drop-async-examples
[INFO] tweaked toml for git repo https://github.com/emk/drop-async-examples written to /workspace/builds/worker-0/source/Cargo.toml
[INFO] crate git repo https://github.com/emk/drop-async-examples already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "CARGO_TARGET_DIR=/opt/rustwide/target" "-e" "CARGO_HOME=/opt/rustwide/cargo-home" "-e" "RUSTUP_HOME=/opt/rustwide/rustup-home" "-w" "/opt/rustwide/workdir" "-m" "1610612736" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] cdd2c116f12550d97fa60e3a5f198c01d90cc8c60071374467203391f751b4b8
[INFO] running `Command { std: "docker" "start" "-a" "cdd2c116f12550d97fa60e3a5f198c01d90cc8c60071374467203391f751b4b8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "cdd2c116f12550d97fa60e3a5f198c01d90cc8c60071374467203391f751b4b8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "cdd2c116f12550d97fa60e3a5f198c01d90cc8c60071374467203391f751b4b8", kill_on_drop: false }`
[INFO] [stdout] cdd2c116f12550d97fa60e3a5f198c01d90cc8c60071374467203391f751b4b8
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/source:/opt/rustwide/workdir:ro,Z" "-v" "/var/lib/crater-agent-workspace/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/var/lib/crater-agent-workspace/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-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" "--user" "0:0" "--network" "none" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 889fc144f9a01f4a38f585328c1cb55ec4a2b16572c873ad3a81277b5a73012c
[INFO] running `Command { std: "docker" "start" "-a" "889fc144f9a01f4a38f585328c1cb55ec4a2b16572c873ad3a81277b5a73012c", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.50
[INFO] [stderr]    Compiling cfg-if v0.1.7
[INFO] [stderr]    Compiling autocfg v0.1.2
[INFO] [stderr]    Compiling futures v0.1.25
[INFO] [stderr]    Compiling lazycell v1.2.1
[INFO] [stderr]    Compiling proc-macro2 v0.4.27
[INFO] [stderr]    Compiling cc v1.0.30
[INFO] [stderr]    Compiling failure_derive v0.1.5
[INFO] [stderr]    Compiling rustc-demangle v0.1.13
[INFO] [stderr]    Compiling rand_jitter v0.1.3
[INFO] [stderr]    Compiling arrayvec v0.4.10
[INFO] [stderr]    Compiling crossbeam-utils v0.6.5
[INFO] [stderr]    Compiling log v0.4.6
[INFO] [stderr]    Compiling rand_pcg v0.1.2
[INFO] [stderr]    Compiling rand_chacha v0.1.1
[INFO] [stderr]    Compiling rand v0.6.5
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]    --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/futures-0.1.25/src/lib.rs:161:34
[INFO] [stdout]     |
[INFO] [stdout] 161 | #![cfg_attr(feature = "nightly", feature(pin))]
[INFO] [stdout]     |                                  ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling backtrace v0.3.14
[INFO] [stderr]    Compiling crossbeam-queue v0.1.2
[INFO] [stderr]    Compiling crossbeam-epoch v0.7.1
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `futures` due to 2 previous errors
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "889fc144f9a01f4a38f585328c1cb55ec4a2b16572c873ad3a81277b5a73012c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "889fc144f9a01f4a38f585328c1cb55ec4a2b16572c873ad3a81277b5a73012c", kill_on_drop: false }`
[INFO] [stdout] 889fc144f9a01f4a38f585328c1cb55ec4a2b16572c873ad3a81277b5a73012c