[INFO] fetching crate remain 0.2.2...
[INFO] testing remain-0.2.2 against 1.49.0 for beta-1.50-1
[INFO] extracting crate remain 0.2.2 into /workspace/builds/worker-14/source
[INFO] validating manifest of crates.io crate remain 0.2.2 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 remain 0.2.2
[INFO] finished tweaking crates.io crate remain 0.2.2
[INFO] tweaked toml for crates.io crate remain 0.2.2 written to /workspace/builds/worker-14/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] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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] 5073398887fb46846be7a1c70915f2fc73c6c7db275f19ee6e04f0b7152ae15d
[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" "5073398887fb46846be7a1c70915f2fc73c6c7db275f19ee6e04f0b7152ae15d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "5073398887fb46846be7a1c70915f2fc73c6c7db275f19ee6e04f0b7152ae15d", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5073398887fb46846be7a1c70915f2fc73c6c7db275f19ee6e04f0b7152ae15d", kill_on_drop: false }`
[INFO] [stdout] 5073398887fb46846be7a1c70915f2fc73c6c7db275f19ee6e04f0b7152ae15d
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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] 6924035e9a72760f3ee2648f9b10dffb97223c07d687f715b7041e75f4d318ba
[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" "6924035e9a72760f3ee2648f9b10dffb97223c07d687f715b7041e75f4d318ba", kill_on_drop: false }`
[INFO] [stderr]    Compiling syn v1.0.57
[INFO] [stderr]    Compiling remain v0.2.2 (/opt/rustwide/workdir)
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 19.63s
[INFO] running `Command { std: "docker" "inspect" "6924035e9a72760f3ee2648f9b10dffb97223c07d687f715b7041e75f4d318ba", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6924035e9a72760f3ee2648f9b10dffb97223c07d687f715b7041e75f4d318ba", kill_on_drop: false }`
[INFO] [stdout] 6924035e9a72760f3ee2648f9b10dffb97223c07d687f715b7041e75f4d318ba
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] e5217d598c9c3c5572116037ea05ed0a365b6d3cb0135e05f85b7fd5ec63dfe6
[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" "e5217d598c9c3c5572116037ea05ed0a365b6d3cb0135e05f85b7fd5ec63dfe6", kill_on_drop: false }`
[INFO] [stderr]    Compiling rustversion v1.0.4
[INFO] [stderr]    Compiling trybuild v1.0.38
[INFO] [stderr]    Compiling dissimilar v1.0.2
[INFO] [stderr]    Compiling glob v0.3.0
[INFO] [stderr]    Compiling termcolor v1.1.2
[INFO] [stderr]    Compiling serde_derive v1.0.118
[INFO] [stderr]    Compiling serde v1.0.118
[INFO] [stderr]    Compiling toml v0.5.8
[INFO] [stderr]    Compiling serde_json v1.0.61
[INFO] [stderr]    Compiling remain v0.2.2 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> tests/unstable.rs:3:1
[INFO] [stdout]   |
[INFO] [stdout] 3 | #![feature(proc_macro_hygiene, stmt_expr_attributes)]
[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 `remain`
[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" "e5217d598c9c3c5572116037ea05ed0a365b6d3cb0135e05f85b7fd5ec63dfe6", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e5217d598c9c3c5572116037ea05ed0a365b6d3cb0135e05f85b7fd5ec63dfe6", kill_on_drop: false }`
[INFO] [stdout] e5217d598c9c3c5572116037ea05ed0a365b6d3cb0135e05f85b7fd5ec63dfe6