[INFO] fetching crate nightfall 0.1.8...
[INFO] testing nightfall-0.1.8 against 1.55.0 for beta-1.56-1
[INFO] extracting crate nightfall 0.1.8 into /workspace/builds/worker-6/source
[INFO] validating manifest of crates.io crate nightfall 0.1.8 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] started tweaking crates.io crate nightfall 0.1.8
[INFO] finished tweaking crates.io crate nightfall 0.1.8
[INFO] tweaked toml for crates.io crate nightfall 0.1.8 written to /workspace/builds/worker-6/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[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-6/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/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] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] b9f79bd5287ee31691842730c924c02c530f24e93274a77e5a5620489d33d5d0
[INFO] running `Command { std: "docker" "start" "-a" "b9f79bd5287ee31691842730c924c02c530f24e93274a77e5a5620489d33d5d0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "b9f79bd5287ee31691842730c924c02c530f24e93274a77e5a5620489d33d5d0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b9f79bd5287ee31691842730c924c02c530f24e93274a77e5a5620489d33d5d0", kill_on_drop: false }`
[INFO] [stdout] b9f79bd5287ee31691842730c924c02c530f24e93274a77e5a5620489d33d5d0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/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] 49e63f241f4f8da887f9d1843bb7c2d4177ff2b311800cdb10dba2a54c27ef30
[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" "49e63f241f4f8da887f9d1843bb7c2d4177ff2b311800cdb10dba2a54c27ef30", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling rustversion v1.0.5
[INFO] [stderr]    Compiling futures-sink v0.3.17
[INFO] [stderr]    Compiling spin v0.7.1
[INFO] [stderr]    Compiling unescape v0.1.0
[INFO] [stderr]    Compiling pollster v0.2.4
[INFO] [stderr]    Compiling futures-util v0.3.17
[INFO] [stderr]    Compiling tokio v1.11.0
[INFO] [stderr]    Compiling spinny v0.2.2
[INFO] [stderr]    Compiling spin v0.9.2
[INFO] [stderr]    Compiling mio v0.7.13
[INFO] [stderr]    Compiling getrandom v0.2.3
[INFO] [stderr]    Compiling nix v0.17.0
[INFO] [stderr]    Compiling derive_more v0.99.16
[INFO] [stderr]    Compiling xtra_proc v0.1.0
[INFO] [stderr]    Compiling barrage v0.2.1
[INFO] [stderr]    Compiling flume v0.10.9
[INFO] [stderr]    Compiling uuid v0.8.2
[INFO] [stderr]    Compiling catty v0.1.4
[INFO] [stderr]    Compiling err-derive v0.3.0
[INFO] [stderr]    Compiling xtra v0.5.1
[INFO] [stderr]    Compiling psutil v3.2.1
[INFO] [stderr]    Compiling tokio-stream v0.1.7
[INFO] [stderr]    Compiling nightfall v0.1.8 (/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(assert_matches, result_flattening, hash_drain_filter)]
[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 `nightfall` due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "49e63f241f4f8da887f9d1843bb7c2d4177ff2b311800cdb10dba2a54c27ef30", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "49e63f241f4f8da887f9d1843bb7c2d4177ff2b311800cdb10dba2a54c27ef30", kill_on_drop: false }`
[INFO] [stdout] 49e63f241f4f8da887f9d1843bb7c2d4177ff2b311800cdb10dba2a54c27ef30