[INFO] fetching crate rxrust 0.10.0...
[INFO] testing rxrust-0.10.0 against 1.49.0 for beta-1.50-1
[INFO] extracting crate rxrust 0.10.0 into /workspace/builds/worker-13/source
[INFO] validating manifest of crates.io crate rxrust 0.10.0 on toolchain 1.49.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate rxrust 0.10.0
[INFO] finished tweaking crates.io crate rxrust 0.10.0
[INFO] tweaked toml for crates.io crate rxrust 0.10.0 written to /workspace/builds/worker-13/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.49.0" "fetch" "--locked" "--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-13/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/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" "rustops/crates-build-env@sha256:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] b6efd7549a9e39d0e497dcc867f0ebefcba4155b7d547827a2ae17a6a4d05b39
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "b6efd7549a9e39d0e497dcc867f0ebefcba4155b7d547827a2ae17a6a4d05b39", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "b6efd7549a9e39d0e497dcc867f0ebefcba4155b7d547827a2ae17a6a4d05b39", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b6efd7549a9e39d0e497dcc867f0ebefcba4155b7d547827a2ae17a6a4d05b39", kill_on_drop: false }`
[INFO] [stdout] b6efd7549a9e39d0e497dcc867f0ebefcba4155b7d547827a2ae17a6a4d05b39
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-13/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" "rustops/crates-build-env@sha256:b8eeb62f26c39b23691079a6cb6de528d8e88b4d71a8f6b1d30f8ba7d9c16de9" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 613fd290651f4ad0abfbecdc4e61983b906b1d12c3a2ae93149f4f3e0e2a957a
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "613fd290651f4ad0abfbecdc4e61983b906b1d12c3a2ae93149f4f3e0e2a957a", kill_on_drop: false }`
[INFO] [stderr]    Compiling futures-lite v1.11.3
[INFO] [stderr]    Compiling signal-hook-registry v1.3.0
[INFO] [stderr]    Compiling futures-util v0.3.8
[INFO] [stderr]    Compiling signal-hook v0.1.17
[INFO] [stderr]    Compiling async-io v1.3.1
[INFO] [stderr]    Compiling async-executor v1.4.0
[INFO] [stderr]    Compiling blocking v1.0.2
[INFO] [stderr]    Compiling async-process v1.0.1
[INFO] [stderr]    Compiling async-global-executor v1.4.3
[INFO] [stderr]    Compiling async-std v1.8.0
[INFO] [stderr]    Compiling futures-executor v0.3.8
[INFO] [stderr]    Compiling futures v0.3.8
[INFO] [stderr]    Compiling rxrust v0.10.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:2:1
[INFO] [stdout]   |
[INFO] [stdout] 2 | / #![feature(
[INFO] [stdout] 3 | |   external_doc,
[INFO] [stdout] 4 | |   min_specialization,
[INFO] [stdout] 5 | |   drain_filter,
[INFO] [stdout] ... |
[INFO] [stdout] 8 | |   generic_associated_types
[INFO] [stdout] 9 | | )]
[INFO] [stdout]   | |__^
[INFO] [stdout] 
[INFO] [stdout] 
[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 `rxrust`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `Command { std: "docker" "inspect" "613fd290651f4ad0abfbecdc4e61983b906b1d12c3a2ae93149f4f3e0e2a957a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "613fd290651f4ad0abfbecdc4e61983b906b1d12c3a2ae93149f4f3e0e2a957a", kill_on_drop: false }`
[INFO] [stdout] 613fd290651f4ad0abfbecdc4e61983b906b1d12c3a2ae93149f4f3e0e2a957a