[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 try#55b3f428b4fac6790b1e8492e0b91ff2d80aec7c for pr-77035
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fsteinsag%2Frust-connect4" "/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/steinsag/rust-connect4 on toolchain 55b3f428b4fac6790b1e8492e0b91ff2d80aec7c
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+55b3f428b4fac6790b1e8492e0b91ff2d80aec7c" "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-0/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" "+55b3f428b4fac6790b1e8492e0b91ff2d80aec7c" "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" "+55b3f428b4fac6790b1e8492e0b91ff2d80aec7c" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] f8bb8a9e8249fff7e5045ebfa4cf93ac556009b7e948b76903b6f5a9e5d715bf
[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" "f8bb8a9e8249fff7e5045ebfa4cf93ac556009b7e948b76903b6f5a9e5d715bf", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "f8bb8a9e8249fff7e5045ebfa4cf93ac556009b7e948b76903b6f5a9e5d715bf", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f8bb8a9e8249fff7e5045ebfa4cf93ac556009b7e948b76903b6f5a9e5d715bf", kill_on_drop: false }`
[INFO] [stdout] f8bb8a9e8249fff7e5045ebfa4cf93ac556009b7e948b76903b6f5a9e5d715bf
[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=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:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+55b3f428b4fac6790b1e8492e0b91ff2d80aec7c" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] b94d5c4f6a3c5660ccf32a64a6231ed32d83bbac40ed8ed51152c80aba782ab5
[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" "b94d5c4f6a3c5660ccf32a64a6231ed32d83bbac40ed8ed51152c80aba782ab5", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling libc v0.2.80
[INFO] [stderr]    Compiling getrandom v0.1.15
[INFO] [stderr]     Checking cfg-if v0.1.10
[INFO] [stderr]     Checking ppv-lite86 v0.2.9
[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: `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: `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: 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: 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: 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 8.02s
[INFO] running `Command { std: "docker" "inspect" "b94d5c4f6a3c5660ccf32a64a6231ed32d83bbac40ed8ed51152c80aba782ab5", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b94d5c4f6a3c5660ccf32a64a6231ed32d83bbac40ed8ed51152c80aba782ab5", kill_on_drop: false }`
[INFO] [stdout] b94d5c4f6a3c5660ccf32a64a6231ed32d83bbac40ed8ed51152c80aba782ab5