[INFO] cloning repository https://github.com/randrews/rustmaze
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/randrews/rustmaze" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Frandrews%2Frustmaze", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Frandrews%2Frustmaze'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] d560ad8c4c82c39f758b025a74ed1bce77d0bd1c
[INFO] testing randrews/rustmaze/d560ad8c4c82c39f758b025a74ed1bce77d0bd1c against master#1871252fc8bb672d40787e67404e6eaae7059369 for pr-125151
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Frandrews%2Frustmaze" "/workspace/builds/worker-2-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-2-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/randrews/rustmaze on toolchain 1871252fc8bb672d40787e67404e6eaae7059369
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1871252fc8bb672d40787e67404e6eaae7059369" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/randrews/rustmaze
[INFO] finished tweaking git repo https://github.com/randrews/rustmaze
[INFO] tweaked toml for git repo https://github.com/randrews/rustmaze written to /workspace/builds/worker-2-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/randrews/rustmaze already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1871252fc8bb672d40787e67404e6eaae7059369" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:beeedbb442662e57d416641ecc3200b38e573c25b057896194468d05594dd835" "/opt/rustwide/cargo-home/bin/cargo" "+1871252fc8bb672d40787e67404e6eaae7059369" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] b7882a3214db7b97f9791bdae9304ef8b927f5db9c0db27c0d8e59c3ac649660
[INFO] running `Command { std: "docker" "start" "-a" "b7882a3214db7b97f9791bdae9304ef8b927f5db9c0db27c0d8e59c3ac649660", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "b7882a3214db7b97f9791bdae9304ef8b927f5db9c0db27c0d8e59c3ac649660", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b7882a3214db7b97f9791bdae9304ef8b927f5db9c0db27c0d8e59c3ac649660", kill_on_drop: false }`
[INFO] [stdout] b7882a3214db7b97f9791bdae9304ef8b927f5db9c0db27c0d8e59c3ac649660
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/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" "RUSTDOCFLAGS=--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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:beeedbb442662e57d416641ecc3200b38e573c25b057896194468d05594dd835" "/opt/rustwide/cargo-home/bin/cargo" "+1871252fc8bb672d40787e67404e6eaae7059369" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 6c78c02626d0c19002295160d86f79a27c48a82743706716556815a3d749c555
[INFO] running `Command { std: "docker" "start" "-a" "6c78c02626d0c19002295160d86f79a27c48a82743706716556815a3d749c555", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.80
[INFO] [stderr]    Compiling getrandom v0.1.15
[INFO] [stderr]    Compiling cfg-if v0.1.10
[INFO] [stderr]    Compiling ppv-lite86 v0.2.10
[INFO] [stderr]    Compiling rand_core v0.5.1
[INFO] [stderr]    Compiling rand_chacha v0.2.2
[INFO] [stderr]    Compiling rand v0.7.3
[INFO] [stderr]    Compiling maze v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `rand::prelude::*`
[INFO] [stdout]  --> src/main.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use rand::prelude::*;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `MazeIterator` is never constructed
[INFO] [stdout]   --> src/main.rs:11:8
[INFO] [stdout]    |
[INFO] [stdout] 11 | struct MazeIterator<'a> { maze: &'a Maze, n: usize }
[INFO] [stdout]    |        ^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: struct `Cell` is never constructed
[INFO] [stdout]   --> src/main.rs:20:8
[INFO] [stdout]    |
[INFO] [stdout] 20 | struct Cell { pub north: bool, pub east: bool, pub south: bool, pub west: bool }
[INFO] [stdout]    |        ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: methods `edge`, `corner`, `iter`, and `cell` are never used
[INFO] [stdout]   --> src/main.rs:42:6
[INFO] [stdout]    |
[INFO] [stdout] 25 | impl Maze {
[INFO] [stdout]    | --------- methods in this implementation
[INFO] [stdout] ...
[INFO] [stdout] 42 |   fn edge(&self, point: Point) -> bool {
[INFO] [stdout]    |      ^^^^
[INFO] [stdout] ...
[INFO] [stdout] 48 |   fn corner(&self, point: Point) -> bool {
[INFO] [stdout]    |      ^^^^^^
[INFO] [stdout] ...
[INFO] [stdout] 71 |   fn iter(&self) -> MazeIterator {
[INFO] [stdout]    |      ^^^^
[INFO] [stdout] ...
[INFO] [stdout] 88 |   fn cell(&self, point: Point) -> Cell {
[INFO] [stdout]    |      ^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 4 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 1.68s
[INFO] running `Command { std: "docker" "inspect" "6c78c02626d0c19002295160d86f79a27c48a82743706716556815a3d749c555", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6c78c02626d0c19002295160d86f79a27c48a82743706716556815a3d749c555", kill_on_drop: false }`
[INFO] [stdout] 6c78c02626d0c19002295160d86f79a27c48a82743706716556815a3d749c555
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/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" "RUSTDOCFLAGS=--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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:beeedbb442662e57d416641ecc3200b38e573c25b057896194468d05594dd835" "/opt/rustwide/cargo-home/bin/cargo" "+1871252fc8bb672d40787e67404e6eaae7059369" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] c413b04f0b94dce8132957ad1ce64eb75ac35633e71f7ed2d188eaed7810be8f
[INFO] running `Command { std: "docker" "start" "-a" "c413b04f0b94dce8132957ad1ce64eb75ac35633e71f7ed2d188eaed7810be8f", kill_on_drop: false }`
[INFO] [stderr]    Compiling maze v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `rand::prelude::*`
[INFO] [stdout]  --> src/main.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use rand::prelude::*;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/main.rs:242:3
[INFO] [stdout]     |
[INFO] [stdout] 242 |   m.carve(Point { x: 0, y: 0 }, Dir::South);
[INFO] [stdout]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 242 |   let _ = m.carve(Point { x: 0, y: 0 }, Dir::South);
[INFO] [stdout]     |   +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/main.rs:243:3
[INFO] [stdout]     |
[INFO] [stdout] 243 |   m.carve(Point { x: 0, y: 1 }, Dir::East);
[INFO] [stdout]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 243 |   let _ = m.carve(Point { x: 0, y: 1 }, Dir::East);
[INFO] [stdout]     |   +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/main.rs:251:3
[INFO] [stdout]     |
[INFO] [stdout] 251 |   m.carve(Point { x: 0, y: 1 }, Dir::North);
[INFO] [stdout]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 251 |   let _ = m.carve(Point { x: 0, y: 1 }, Dir::North);
[INFO] [stdout]     |   +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/main.rs:252:3
[INFO] [stdout]     |
[INFO] [stdout] 252 |   m.carve(Point { x: 1, y: 0 }, Dir::West);
[INFO] [stdout]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 252 |   let _ = m.carve(Point { x: 1, y: 0 }, Dir::West);
[INFO] [stdout]     |   +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/main.rs:262:3
[INFO] [stdout]     |
[INFO] [stdout] 262 |   m.carve(Point { x: 0, y: 1 }, Dir::North);
[INFO] [stdout]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 262 |   let _ = m.carve(Point { x: 0, y: 1 }, Dir::North);
[INFO] [stdout]     |   +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/main.rs:263:3
[INFO] [stdout]     |
[INFO] [stdout] 263 |   m.carve(Point { x: 1, y: 0 }, Dir::West);
[INFO] [stdout]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] help: use `let _ = ...` to ignore the resulting value
[INFO] [stdout]     |
[INFO] [stdout] 263 |   let _ = m.carve(Point { x: 1, y: 0 }, Dir::West);
[INFO] [stdout]     |   +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `test` profile [unoptimized + debuginfo] target(s) in 0.36s
[INFO] running `Command { std: "docker" "inspect" "c413b04f0b94dce8132957ad1ce64eb75ac35633e71f7ed2d188eaed7810be8f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c413b04f0b94dce8132957ad1ce64eb75ac35633e71f7ed2d188eaed7810be8f", kill_on_drop: false }`
[INFO] [stdout] c413b04f0b94dce8132957ad1ce64eb75ac35633e71f7ed2d188eaed7810be8f
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-2-tc1/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" "RUSTDOCFLAGS=--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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:beeedbb442662e57d416641ecc3200b38e573c25b057896194468d05594dd835" "/opt/rustwide/cargo-home/bin/cargo" "+1871252fc8bb672d40787e67404e6eaae7059369" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] 630cf950574d6c409f855f592488ba6de17aac89e745cdfe8af7d3d6a0bf7728
[INFO] running `Command { std: "docker" "start" "-a" "630cf950574d6c409f855f592488ba6de17aac89e745cdfe8af7d3d6a0bf7728", kill_on_drop: false }`
[INFO] [stderr] warning: unused import: `rand::prelude::*`
[INFO] [stderr]  --> src/main.rs:1:5
[INFO] [stderr]   |
[INFO] [stderr] 1 | use rand::prelude::*;
[INFO] [stderr]   |     ^^^^^^^^^^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/main.rs:242:3
[INFO] [stderr]     |
[INFO] [stderr] 242 |   m.carve(Point { x: 0, y: 0 }, Dir::South);
[INFO] [stderr]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stderr] help: use `let _ = ...` to ignore the resulting value
[INFO] [stderr]     |
[INFO] [stderr] 242 |   let _ = m.carve(Point { x: 0, y: 0 }, Dir::South);
[INFO] [stderr]     |   +++++++
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/main.rs:243:3
[INFO] [stderr]     |
[INFO] [stderr] 243 |   m.carve(Point { x: 0, y: 1 }, Dir::East);
[INFO] [stderr]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr] help: use `let _ = ...` to ignore the resulting value
[INFO] [stderr]     |
[INFO] [stderr] 243 |   let _ = m.carve(Point { x: 0, y: 1 }, Dir::East);
[INFO] [stderr]     |   +++++++
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/main.rs:251:3
[INFO] [stderr]     |
[INFO] [stderr] 251 |   m.carve(Point { x: 0, y: 1 }, Dir::North);
[INFO] [stderr]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr] help: use `let _ = ...` to ignore the resulting value
[INFO] [stderr]     |
[INFO] [stderr] 251 |   let _ = m.carve(Point { x: 0, y: 1 }, Dir::North);
[INFO] [stderr]     |   +++++++
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/main.rs:252:3
[INFO] [stderr]     |
[INFO] [stderr] 252 |   m.carve(Point { x: 1, y: 0 }, Dir::West);
[INFO] [stderr]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr] help: use `let _ = ...` to ignore the resulting value
[INFO] [stderr]     |
[INFO] [stderr] 252 |   let _ = m.carve(Point { x: 1, y: 0 }, Dir::West);
[INFO] [stderr]     |   +++++++
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/main.rs:262:3
[INFO] [stderr]     |
[INFO] [stderr] 262 |   m.carve(Point { x: 0, y: 1 }, Dir::North);
[INFO] [stderr]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr] help: use `let _ = ...` to ignore the resulting value
[INFO] [stderr]     |
[INFO] [stderr] 262 |   let _ = m.carve(Point { x: 0, y: 1 }, Dir::North);
[INFO] [stderr]     |   +++++++
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/main.rs:263:3
[INFO] [stderr]     |
[INFO] [stderr] 263 |   m.carve(Point { x: 1, y: 0 }, Dir::West);
[INFO] [stderr]     |   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr] help: use `let _ = ...` to ignore the resulting value
[INFO] [stderr]     |
[INFO] [stderr] 263 |   let _ = m.carve(Point { x: 1, y: 0 }, Dir::West);
[INFO] [stderr]     |   +++++++
[INFO] [stderr] 
[INFO] [stderr] warning: `maze` (bin "maze" test) generated 7 warnings (run `cargo fix --bin "maze" --tests` to apply 1 suggestion)
[INFO] [stderr]     Finished `test` profile [unoptimized + debuginfo] target(s) in 0.01s
[INFO] [stderr]      Running unittests src/main.rs (/opt/rustwide/target/debug/deps/maze-cb4ddcdc84df4d53)
[INFO] [stdout] 
[INFO] [stdout] running 6 tests
[INFO] [stdout] test maze_carve_passage_test ... ok
[INFO] [stdout] test maze_cell_test ... ok
[INFO] [stdout] test maze_iterator_test ... ok
[INFO] [stdout] test maze_neighbor_test ... ok
[INFO] [stdout] test maze_point_tests ... ok
[INFO] [stdout] test point_translate_test ... ok
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 6 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "630cf950574d6c409f855f592488ba6de17aac89e745cdfe8af7d3d6a0bf7728", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "630cf950574d6c409f855f592488ba6de17aac89e745cdfe8af7d3d6a0bf7728", kill_on_drop: false }`
[INFO] [stdout] 630cf950574d6c409f855f592488ba6de17aac89e745cdfe8af7d3d6a0bf7728