[INFO] cloning repository https://github.com/steinsag/rust-connect4
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/steinsag/rust-connect4" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fsteinsag%2Frust-connect4", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fsteinsag%2Frust-connect4'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] d9d3f098247097ab3f65e5006b1196bb331e82e7
[INFO] checking steinsag/rust-connect4 against beta for pr-78714
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fsteinsag%2Frust-connect4" "/workspace/builds/worker-3/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/steinsag/rust-connect4 on toolchain beta
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/steinsag/rust-connect4
[INFO] finished tweaking git repo https://github.com/steinsag/rust-connect4
[INFO] tweaked toml for git repo https://github.com/steinsag/rust-connect4 written to /workspace/builds/worker-3/source/Cargo.toml
[INFO] crate git repo https://github.com/steinsag/rust-connect4 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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@sha256:6eabd152ff4036248d66efda456a36cb33d24b7291b33f25f75140726c88da35" "/opt/rustwide/cargo-home/bin/cargo" "+beta" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] f1cb7e283d26f632cc4c79aa8d6fe6c1ff690f38b26b038e8c7900764d2d798e
[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" "f1cb7e283d26f632cc4c79aa8d6fe6c1ff690f38b26b038e8c7900764d2d798e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "f1cb7e283d26f632cc4c79aa8d6fe6c1ff690f38b26b038e8c7900764d2d798e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f1cb7e283d26f632cc4c79aa8d6fe6c1ff690f38b26b038e8c7900764d2d798e", kill_on_drop: false }`
[INFO] [stdout] f1cb7e283d26f632cc4c79aa8d6fe6c1ff690f38b26b038e8c7900764d2d798e
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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@sha256:6eabd152ff4036248d66efda456a36cb33d24b7291b33f25f75140726c88da35" "/opt/rustwide/cargo-home/bin/cargo" "+beta" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 9c0eb004a8eaa14c48cf24ec8e78aa3941a372f06d5175da0fcea19eb96a71a0
[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" "9c0eb004a8eaa14c48cf24ec8e78aa3941a372f06d5175da0fcea19eb96a71a0", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling libc v0.2.80
[INFO] [stderr]     Checking getrandom v0.1.15
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking rand_chacha v0.2.2
[INFO] [stderr]     Checking rand v0.7.3
[INFO] [stderr]     Checking connect4 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `temporary_game_field`
[INFO] [stdout]   --> src/strategy/back_propagation.rs:18:13
[INFO] [stdout]    |
[INFO] [stdout] 18 |         let mut temporary_game_field = board.clone();
[INFO] [stdout]    |             ^^^^^^^^^^^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_temporary_game_field`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `temporary_game_field`
[INFO] [stdout]   --> src/strategy/back_propagation.rs:18:13
[INFO] [stdout]    |
[INFO] [stdout] 18 |         let mut temporary_game_field = board.clone();
[INFO] [stdout]    |             ^^^^^^^^^^^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_temporary_game_field`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `col`
[INFO] [stdout]   --> src/strategy/back_propagation.rs:19:13
[INFO] [stdout]    |
[INFO] [stdout] 19 |         for col in 0..COLS {}
[INFO] [stdout]    |             ^^^ help: if this is intentional, prefix it with an underscore: `_col`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `col`
[INFO] [stdout]   --> src/strategy/back_propagation.rs:19:13
[INFO] [stdout]    |
[INFO] [stdout] 19 |         for col in 0..COLS {}
[INFO] [stdout]    |             ^^^ help: if this is intentional, prefix it with an underscore: `_col`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/strategy/back_propagation.rs:18:13
[INFO] [stdout]    |
[INFO] [stdout] 18 |         let mut temporary_game_field = board.clone();
[INFO] [stdout]    |             ----^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |             |
[INFO] [stdout]    |             help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/strategy/back_propagation.rs:18:13
[INFO] [stdout]    |
[INFO] [stdout] 18 |         let mut temporary_game_field = board.clone();
[INFO] [stdout]    |             ----^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |             |
[INFO] [stdout]    |             help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `pushed_columns`
[INFO] [stdout]  --> src/strategy/back_propagation.rs:5:5
[INFO] [stdout]   |
[INFO] [stdout] 5 |     pushed_columns: Vec<u8>,
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `pushed_columns`
[INFO] [stdout]  --> src/strategy/back_propagation.rs:5:5
[INFO] [stdout]   |
[INFO] [stdout] 5 |     pushed_columns: Vec<u8>,
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 4 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 4 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 5.79s
[INFO] running `Command { std: "docker" "inspect" "9c0eb004a8eaa14c48cf24ec8e78aa3941a372f06d5175da0fcea19eb96a71a0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9c0eb004a8eaa14c48cf24ec8e78aa3941a372f06d5175da0fcea19eb96a71a0", kill_on_drop: false }`
[INFO] [stdout] 9c0eb004a8eaa14c48cf24ec8e78aa3941a372f06d5175da0fcea19eb96a71a0