[INFO] fetching crate jam 0.0.1...
[INFO] testing jam-0.0.1 against 1.49.0 for beta-1.50-1
[INFO] extracting crate jam 0.0.1 into /workspace/builds/worker-0/source
[INFO] validating manifest of crates.io crate jam 0.0.1 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 jam 0.0.1
[INFO] finished tweaking crates.io crate jam 0.0.1
[INFO] tweaked toml for crates.io crate jam 0.0.1 written to /workspace/builds/worker-0/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-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" "rustops/crates-build-env@sha256:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "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] e9c6409b499428ded0869b439155e829df1397294668da10d397f3c9486095d5
[INFO] running `Command { std: "docker" "start" "-a" "e9c6409b499428ded0869b439155e829df1397294668da10d397f3c9486095d5", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "e9c6409b499428ded0869b439155e829df1397294668da10d397f3c9486095d5", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e9c6409b499428ded0869b439155e829df1397294668da10d397f3c9486095d5", kill_on_drop: false }`
[INFO] [stdout] e9c6409b499428ded0869b439155e829df1397294668da10d397f3c9486095d5
[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" "rustops/crates-build-env@sha256:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+1.49.0" "build" "--frozen" "--message-format=json", 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] e70b4fe373b72959b723f75492bb2e7e246443b96ce84f87b077d0394caee356
[INFO] running `Command { std: "docker" "start" "-a" "e70b4fe373b72959b723f75492bb2e7e246443b96ce84f87b077d0394caee356", kill_on_drop: false }`
[INFO] [stderr]    Compiling serde v0.9.15
[INFO] [stderr]    Compiling syn v0.11.11
[INFO] [stderr]    Compiling num-traits v0.1.43
[INFO] [stderr]    Compiling serde_codegen_internals v0.14.2
[INFO] [stderr]    Compiling bincode v0.7.0
[INFO] [stderr]    Compiling jam_derive v0.0.1
[INFO] [stderr]    Compiling serde_derive v0.9.15
[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/jam_derive-0.0.1/src/lib.rs:34:1
[INFO] [stdout]    |
[INFO] [stdout] 34 | #![feature(proc_macro, proc_macro_lib)]
[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 `jam_derive`
[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" "e70b4fe373b72959b723f75492bb2e7e246443b96ce84f87b077d0394caee356", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e70b4fe373b72959b723f75492bb2e7e246443b96ce84f87b077d0394caee356", kill_on_drop: false }`
[INFO] [stdout] e70b4fe373b72959b723f75492bb2e7e246443b96ce84f87b077d0394caee356