[INFO] cloning repository https://github.com/aloggia/rust-chip8
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/aloggia/rust-chip8" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Faloggia%2Frust-chip8", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Faloggia%2Frust-chip8'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 7eb11b62d2f785ffced6895e0294b3881331626b
[INFO] testing aloggia/rust-chip8 against 1.55.0 for beta-1.56-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Faloggia%2Frust-chip8" "/workspace/builds/worker-12/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-12/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/aloggia/rust-chip8 on toolchain 1.55.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/aloggia/rust-chip8
[INFO] finished tweaking git repo https://github.com/aloggia/rust-chip8
[INFO] tweaked toml for git repo https://github.com/aloggia/rust-chip8 written to /workspace/builds/worker-12/source/Cargo.toml
[INFO] crate git repo https://github.com/aloggia/rust-chip8 already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] b0315a009c576fe22e685b1e4867ccb9b741c49c659979cba5bf0ed08245206b
[INFO] running `Command { std: "docker" "start" "-a" "b0315a009c576fe22e685b1e4867ccb9b741c49c659979cba5bf0ed08245206b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "b0315a009c576fe22e685b1e4867ccb9b741c49c659979cba5bf0ed08245206b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b0315a009c576fe22e685b1e4867ccb9b741c49c659979cba5bf0ed08245206b", kill_on_drop: false }`
[INFO] [stdout] b0315a009c576fe22e685b1e4867ccb9b741c49c659979cba5bf0ed08245206b
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] c04035cab7b6ed33d561cfa01e7b21ee49960d8b49cc81fe870cf93898c06885
[INFO] running `Command { std: "docker" "start" "-a" "c04035cab7b6ed33d561cfa01e7b21ee49960d8b49cc81fe870cf93898c06885", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.95
[INFO] [stderr]    Compiling proc-macro2 v1.0.27
[INFO] [stderr]    Compiling log v0.4.14
[INFO] [stderr]    Compiling xml-rs v0.8.3
[INFO] [stderr]    Compiling humantime v2.1.0
[INFO] [stderr]    Compiling bindgen v0.56.0
[INFO] [stderr]    Compiling shlex v0.1.1
[INFO] [stderr]    Compiling once_cell v1.7.2
[INFO] [stderr]    Compiling downcast-rs v1.2.0
[INFO] [stderr]    Compiling cc v1.0.68
[INFO] [stderr]    Compiling nom v5.1.2
[INFO] [stderr]    Compiling wayland-sys v0.28.5
[INFO] [stderr]    Compiling nom v6.1.2
[INFO] [stderr]    Compiling x11-dl v2.18.5
[INFO] [stderr]    Compiling clang-sys v1.2.0
[INFO] [stderr]    Compiling aho-corasick v0.7.18
[INFO] [stderr]    Compiling quote v1.0.9
[INFO] [stderr]    Compiling minifb v0.19.3
[INFO] [stderr]    Compiling wayland-scanner v0.28.5
[INFO] [stderr]    Compiling regex v1.5.4
[INFO] [stderr]    Compiling atty v0.2.14
[INFO] [stderr]    Compiling which v3.1.1
[INFO] [stderr]    Compiling getrandom v0.2.3
[INFO] [stderr]    Compiling nix v0.20.0
[INFO] [stderr]    Compiling rand v0.4.6
[INFO] [stderr]    Compiling raw-window-handle v0.3.3
[INFO] [stderr]    Compiling cexpr v0.4.0
[INFO] [stderr]    Compiling clap v2.33.3
[INFO] [stderr]    Compiling rand_core v0.6.2
[INFO] [stderr]    Compiling rand_chacha v0.3.0
[INFO] [stderr]    Compiling rand v0.3.23
[INFO] [stderr]    Compiling xcursor v0.3.3
[INFO] [stderr]    Compiling wayland-client v0.28.5
[INFO] [stderr]    Compiling wayland-protocols v0.28.5
[INFO] [stderr]    Compiling rand v0.8.3
[INFO] [stderr]    Compiling env_logger v0.8.3
[INFO] [stderr]    Compiling tempfile v3.2.0
[INFO] [stderr]    Compiling wayland-commons v0.28.5
[INFO] [stderr]    Compiling wayland-cursor v0.28.5
[INFO] [stderr]    Compiling xkbcommon-sys v0.7.5
[INFO] [stderr]    Compiling xkb v0.2.1
[INFO] [stderr]    Compiling rust-chip8 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused imports: `KeyRepeat`, `Key`, `Window`
[INFO] [stdout]  --> src/keyboard.rs:1:14
[INFO] [stdout]   |
[INFO] [stdout] 1 | use minifb::{Window, KeyRepeat, Key};
[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:120:13
[INFO] [stdout]     |
[INFO] [stdout] 120 |             window.update_with_buffer(&buffer, width, height);
[INFO] [stdout]     |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: comparison is useless due to type limits
[INFO] [stdout]    --> src/cpu.rs:169:28
[INFO] [stdout]     |
[INFO] [stdout] 169 |                         if diff < 0 {
[INFO] [stdout]     |                            ^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_comparisons)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/cpu.rs:342:9
[INFO] [stdout]     |
[INFO] [stdout] 342 |         write!(f, "\n{:#X}\n", self.pc);
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/cpu.rs:343:9
[INFO] [stdout]     |
[INFO] [stdout] 343 |         write!(f, "vx: ");
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/cpu.rs:345:13
[INFO] [stdout]     |
[INFO] [stdout] 345 |             write!(f, "{:#X}", *item);
[INFO] [stdout]     |             ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/cpu.rs:347:9
[INFO] [stdout]     |
[INFO] [stdout] 347 |         write!(f, "\n");
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 56.44s
[INFO] running `Command { std: "docker" "inspect" "c04035cab7b6ed33d561cfa01e7b21ee49960d8b49cc81fe870cf93898c06885", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c04035cab7b6ed33d561cfa01e7b21ee49960d8b49cc81fe870cf93898c06885", kill_on_drop: false }`
[INFO] [stdout] c04035cab7b6ed33d561cfa01e7b21ee49960d8b49cc81fe870cf93898c06885
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 27adb42c58f9e66de08e2d332d9ee0d16fe5bea316520718fd68b28fb6f31f1c
[INFO] running `Command { std: "docker" "start" "-a" "27adb42c58f9e66de08e2d332d9ee0d16fe5bea316520718fd68b28fb6f31f1c", kill_on_drop: false }`
[INFO] [stderr]    Compiling rust-chip8 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused imports: `KeyRepeat`, `Key`, `Window`
[INFO] [stdout]  --> src/keyboard.rs:1:14
[INFO] [stdout]   |
[INFO] [stdout] 1 | use minifb::{Window, KeyRepeat, Key};
[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:120:13
[INFO] [stdout]     |
[INFO] [stdout] 120 |             window.update_with_buffer(&buffer, width, height);
[INFO] [stdout]     |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: comparison is useless due to type limits
[INFO] [stdout]    --> src/cpu.rs:169:28
[INFO] [stdout]     |
[INFO] [stdout] 169 |                         if diff < 0 {
[INFO] [stdout]     |                            ^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_comparisons)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/cpu.rs:342:9
[INFO] [stdout]     |
[INFO] [stdout] 342 |         write!(f, "\n{:#X}\n", self.pc);
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/cpu.rs:343:9
[INFO] [stdout]     |
[INFO] [stdout] 343 |         write!(f, "vx: ");
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/cpu.rs:345:13
[INFO] [stdout]     |
[INFO] [stdout] 345 |             write!(f, "{:#X}", *item);
[INFO] [stdout]     |             ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/cpu.rs:347:9
[INFO] [stdout]     |
[INFO] [stdout] 347 |         write!(f, "\n");
[INFO] [stdout]     |         ^^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.95s
[INFO] running `Command { std: "docker" "inspect" "27adb42c58f9e66de08e2d332d9ee0d16fe5bea316520718fd68b28fb6f31f1c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "27adb42c58f9e66de08e2d332d9ee0d16fe5bea316520718fd68b28fb6f31f1c", kill_on_drop: false }`
[INFO] [stdout] 27adb42c58f9e66de08e2d332d9ee0d16fe5bea316520718fd68b28fb6f31f1c
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-12/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] 48033402be00af0cf25a0922951ced6ab51afa77c5da8c46ba2203d2f927e969
[INFO] running `Command { std: "docker" "start" "-a" "48033402be00af0cf25a0922951ced6ab51afa77c5da8c46ba2203d2f927e969", kill_on_drop: false }`
[INFO] [stderr] warning: unused imports: `KeyRepeat`, `Key`, `Window`
[INFO] [stderr]  --> src/keyboard.rs:1:14
[INFO] [stderr]   |
[INFO] [stderr] 1 | use minifb::{Window, KeyRepeat, Key};
[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:120:13
[INFO] [stderr]     |
[INFO] [stderr] 120 |             window.update_with_buffer(&buffer, width, height);
[INFO] [stderr]     |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr] 
[INFO] [stderr] warning: comparison is useless due to type limits
[INFO] [stderr]    --> src/cpu.rs:169:28
[INFO] [stderr]     |
[INFO] [stderr] 169 |                         if diff < 0 {
[INFO] [stderr]     |                            ^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: `#[warn(unused_comparisons)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/cpu.rs:342:9
[INFO] [stderr]     |
[INFO] [stderr] 342 |         write!(f, "\n{:#X}\n", self.pc);
[INFO] [stderr]     |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/cpu.rs:343:9
[INFO] [stderr]     |
[INFO] [stderr] 343 |         write!(f, "vx: ");
[INFO] [stderr]     |         ^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/cpu.rs:345:13
[INFO] [stderr]     |
[INFO] [stderr] 345 |             write!(f, "{:#X}", *item);
[INFO] [stderr]     |             ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/cpu.rs:347:9
[INFO] [stderr]     |
[INFO] [stderr] 347 |         write!(f, "\n");
[INFO] [stderr]     |         ^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr]     = note: this warning originates in the macro `write` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stderr] 
[INFO] [stderr] warning: `rust-chip8` (bin "rust-chip8" test) generated 7 warnings
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.11s
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/rust_chip8-aaa8cd730e194d9d)
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "48033402be00af0cf25a0922951ced6ab51afa77c5da8c46ba2203d2f927e969", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "48033402be00af0cf25a0922951ced6ab51afa77c5da8c46ba2203d2f927e969", kill_on_drop: false }`
[INFO] [stdout] 48033402be00af0cf25a0922951ced6ab51afa77c5da8c46ba2203d2f927e969