[INFO] cloning repository https://github.com/fahrenkrug/rust_learn_book_errors
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/fahrenkrug/rust_learn_book_errors" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffahrenkrug%2Frust_learn_book_errors", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffahrenkrug%2Frust_learn_book_errors'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] aa959a404d3e1af5bf3df0465fa974898c211764
[INFO] checking fahrenkrug/rust_learn_book_errors against master#c5fbcd35a8217a17f6b63a22217ace06cf8f5f02 for pr-86194
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffahrenkrug%2Frust_learn_book_errors" "/workspace/builds/worker-15/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-15/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/fahrenkrug/rust_learn_book_errors on toolchain c5fbcd35a8217a17f6b63a22217ace06cf8f5f02
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+c5fbcd35a8217a17f6b63a22217ace06cf8f5f02" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/fahrenkrug/rust_learn_book_errors
[INFO] finished tweaking git repo https://github.com/fahrenkrug/rust_learn_book_errors
[INFO] tweaked toml for git repo https://github.com/fahrenkrug/rust_learn_book_errors written to /workspace/builds/worker-15/source/Cargo.toml
[INFO] crate git repo https://github.com/fahrenkrug/rust_learn_book_errors already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+c5fbcd35a8217a17f6b63a22217ace06cf8f5f02" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/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@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+c5fbcd35a8217a17f6b63a22217ace06cf8f5f02" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] c947a952eb8e4e3f976de5a1933b6831875a103cb305763a296c3e7b861c4430
[INFO] running `Command { std: "docker" "start" "-a" "c947a952eb8e4e3f976de5a1933b6831875a103cb305763a296c3e7b861c4430", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "c947a952eb8e4e3f976de5a1933b6831875a103cb305763a296c3e7b861c4430", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "c947a952eb8e4e3f976de5a1933b6831875a103cb305763a296c3e7b861c4430", kill_on_drop: false }`
[INFO] [stdout] c947a952eb8e4e3f976de5a1933b6831875a103cb305763a296c3e7b861c4430
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+c5fbcd35a8217a17f6b63a22217ace06cf8f5f02" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 6d2e7f08d0807cbd2371e997d6b937e18f53ce0da69e5d98d8f817daed23fa16
[INFO] running `Command { std: "docker" "start" "-a" "6d2e7f08d0807cbd2371e997d6b937e18f53ce0da69e5d98d8f817daed23fa16", kill_on_drop: false }`
[INFO] [stderr]     Checking errors v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `f`
[INFO] [stdout]   --> src/main.rs:65:9
[INFO] [stdout]    |
[INFO] [stdout] 65 |     let f = File::open("hello.txt")?;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_f`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `read_username_from_file`
[INFO] [stdout]   --> src/main.rs:69:4
[INFO] [stdout]    |
[INFO] [stdout] 69 | fn read_username_from_file() -> Result<String, io::Error> {
[INFO] [stdout]    |    ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `f`
[INFO] [stdout]   --> src/main.rs:65:9
[INFO] [stdout]    |
[INFO] [stdout] 65 |     let f = File::open("hello.txt")?;
[INFO] [stdout]    |         ^ help: if this is intentional, prefix it with an underscore: `_f`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: function is never used: `read_username_from_file`
[INFO] [stdout]   --> src/main.rs:69:4
[INFO] [stdout]    |
[INFO] [stdout] 69 | fn read_username_from_file() -> Result<String, io::Error> {
[INFO] [stdout]    |    ^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.31s
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "6d2e7f08d0807cbd2371e997d6b937e18f53ce0da69e5d98d8f817daed23fa16", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6d2e7f08d0807cbd2371e997d6b937e18f53ce0da69e5d98d8f817daed23fa16", kill_on_drop: false }`
[INFO] [stdout] 6d2e7f08d0807cbd2371e997d6b937e18f53ce0da69e5d98d8f817daed23fa16