[INFO] cloning repository https://github.com/sambrolia/play_ground
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/sambrolia/play_ground" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fsambrolia%2Fplay_ground", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fsambrolia%2Fplay_ground'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] cf849fb9e55de7d173931e3a6e0ab86c22698ecf
[INFO] checking sambrolia/play_ground against try#ffa4a0215752773248fb0f0a8092f1c3e7907e9e for pr-75585
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fsambrolia%2Fplay_ground" "/workspace/builds/worker-4/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/sambrolia/play_ground on toolchain ffa4a0215752773248fb0f0a8092f1c3e7907e9e
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+ffa4a0215752773248fb0f0a8092f1c3e7907e9e" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/sambrolia/play_ground
[INFO] finished tweaking git repo https://github.com/sambrolia/play_ground
[INFO] tweaked toml for git repo https://github.com/sambrolia/play_ground written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] crate git repo https://github.com/sambrolia/play_ground already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+ffa4a0215752773248fb0f0a8092f1c3e7907e9e" "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-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+ffa4a0215752773248fb0f0a8092f1c3e7907e9e" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] fb1a8b3ddf499f43b0a4d66d3d29a017b93a586bcf694e5e7a40e7d9ae834874
[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" "fb1a8b3ddf499f43b0a4d66d3d29a017b93a586bcf694e5e7a40e7d9ae834874", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "fb1a8b3ddf499f43b0a4d66d3d29a017b93a586bcf694e5e7a40e7d9ae834874", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "fb1a8b3ddf499f43b0a4d66d3d29a017b93a586bcf694e5e7a40e7d9ae834874", kill_on_drop: false }`
[INFO] [stdout] fb1a8b3ddf499f43b0a4d66d3d29a017b93a586bcf694e5e7a40e7d9ae834874
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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=forbid" "-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:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+ffa4a0215752773248fb0f0a8092f1c3e7907e9e" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 06e1af2ebe214f545d46c13694d38ff9c60c735ca78f1ed68d52f0dde2076dfe
[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" "06e1af2ebe214f545d46c13694d38ff9c60c735ca78f1ed68d52f0dde2076dfe", kill_on_drop: false }`
[INFO] [stderr]     Checking play_ground v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/main.rs:54:9
[INFO] [stdout]    |
[INFO] [stdout] 54 |     let x = 1;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]   --> src/main.rs:56:13
[INFO] [stdout]    |
[INFO] [stdout] 56 |         let a = 10;
[INFO] [stdout]    |             ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/main.rs:54:9
[INFO] [stdout]    |
[INFO] [stdout] 54 |     let x = 1;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `a`
[INFO] [stdout]   --> src/main.rs:56:13
[INFO] [stdout]    |
[INFO] [stdout] 56 |         let a = 10;
[INFO] [stdout]    |             ^ help: if this is intentional, prefix it with an underscore: `_a`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.30s
[INFO] running `Command { std: "docker" "inspect" "06e1af2ebe214f545d46c13694d38ff9c60c735ca78f1ed68d52f0dde2076dfe", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "06e1af2ebe214f545d46c13694d38ff9c60c735ca78f1ed68d52f0dde2076dfe", kill_on_drop: false }`
[INFO] [stdout] 06e1af2ebe214f545d46c13694d38ff9c60c735ca78f1ed68d52f0dde2076dfe