[INFO] cloning repository https://github.com/plorefice/b2048
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/plorefice/b2048" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fplorefice%2Fb2048", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fplorefice%2Fb2048'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 7c0b69071e81abb9bdb12a77ab73f33af61b8576
[INFO] testing plorefice/b2048 against beta-2021-01-01 for beta-1.50-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fplorefice%2Fb2048" "/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/plorefice/b2048 on toolchain beta-2021-01-01
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-01-01" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/plorefice/b2048
[INFO] finished tweaking git repo https://github.com/plorefice/b2048
[INFO] tweaked toml for git repo https://github.com/plorefice/b2048 written to /workspace/builds/worker-0/source/Cargo.toml
[INFO] crate git repo https://github.com/plorefice/b2048 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-01-01" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded owning_ref v0.3.3
[INFO] [stderr]   Downloaded unicode-segmentation v1.2.0
[INFO] [stderr]   Downloaded cursive v0.7.5
[INFO] [stderr]   Downloaded stable_deref_trait v1.0.0
[INFO] [stderr]   Downloaded ncurses v5.91.0
[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" "+beta-2021-01-01" "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] a8dfde3a4ace89f963976c534a12c07a07b6114e70c5d8d6296235d7f91cb179
[INFO] running `Command { std: "docker" "start" "-a" "a8dfde3a4ace89f963976c534a12c07a07b6114e70c5d8d6296235d7f91cb179", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "a8dfde3a4ace89f963976c534a12c07a07b6114e70c5d8d6296235d7f91cb179", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a8dfde3a4ace89f963976c534a12c07a07b6114e70c5d8d6296235d7f91cb179", kill_on_drop: false }`
[INFO] [stdout] a8dfde3a4ace89f963976c534a12c07a07b6114e70c5d8d6296235d7f91cb179
[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" "+beta-2021-01-01" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 937fdea1002167f94d7faa957f2f243aaf28d3802e6b8cd12a9be4f83e7f0a04
[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" "937fdea1002167f94d7faa957f2f243aaf28d3802e6b8cd12a9be4f83e7f0a04", kill_on_drop: false }`
[INFO] [stderr]    Compiling num-traits v0.1.42
[INFO] [stderr]    Compiling libc v0.2.36
[INFO] [stderr]    Compiling rustc-serialize v0.3.24
[INFO] [stderr]    Compiling serde v1.0.27
[INFO] [stderr]    Compiling stable_deref_trait v1.0.0
[INFO] [stderr]    Compiling maplit v1.0.1
[INFO] [stderr]    Compiling unicode-segmentation v1.2.0
[INFO] [stderr]    Compiling ncurses v5.91.0
[INFO] [stderr]    Compiling owning_ref v0.3.3
[INFO] [stderr]    Compiling num-integer v0.1.35
[INFO] [stderr]    Compiling rand v0.3.20
[INFO] [stderr]    Compiling num-iter v0.1.34
[INFO] [stderr]    Compiling num-bigint v0.1.41
[INFO] [stderr]    Compiling num-complex v0.1.41
[INFO] [stderr]    Compiling num-rational v0.1.41
[INFO] [stderr]    Compiling toml v0.4.5
[INFO] [stderr]    Compiling num v0.1.41
[INFO] [stderr]    Compiling cursive v0.7.5
[INFO] [stderr]    Compiling b2048 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the beta release channel
[INFO] [stdout]  --> src/main.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(conservative_impl_trait)]
[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 `b2048`
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `Command { std: "docker" "inspect" "937fdea1002167f94d7faa957f2f243aaf28d3802e6b8cd12a9be4f83e7f0a04", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "937fdea1002167f94d7faa957f2f243aaf28d3802e6b8cd12a9be4f83e7f0a04", kill_on_drop: false }`
[INFO] [stdout] 937fdea1002167f94d7faa957f2f243aaf28d3802e6b8cd12a9be4f83e7f0a04