[INFO] cloning repository https://github.com/KarYuKuan/ch16_reference_execise_03
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/KarYuKuan/ch16_reference_execise_03" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FKarYuKuan%2Fch16_reference_execise_03", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FKarYuKuan%2Fch16_reference_execise_03'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 9ab44dfcf67d1ee6952922ed782b8d7ac6d9f928
[INFO] checking KarYuKuan/ch16_reference_execise_03 against try#f27166d4c64dc29edc5ea3214357f191edf8b635 for pr-148329
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FKarYuKuan%2Fch16_reference_execise_03" "/workspace/builds/worker-3-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3-tc2/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/KarYuKuan/ch16_reference_execise_03
[INFO] finished tweaking git repo https://github.com/KarYuKuan/ch16_reference_execise_03
[INFO] tweaked toml for git repo https://github.com/KarYuKuan/ch16_reference_execise_03 written to /workspace/builds/worker-3-tc2/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/KarYuKuan/ch16_reference_execise_03 on toolchain f27166d4c64dc29edc5ea3214357f191edf8b635
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+f27166d4c64dc29edc5ea3214357f191edf8b635" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/KarYuKuan/ch16_reference_execise_03 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" "+f27166d4c64dc29edc5ea3214357f191edf8b635" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[ERROR] error running command: no output for 300 seconds
[INFO] checking KarYuKuan/ch16_reference_execise_03 against try#f27166d4c64dc29edc5ea3214357f191edf8b635 for pr-148329
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FKarYuKuan%2Fch16_reference_execise_03" "/workspace/builds/worker-3-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-3-tc2/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/KarYuKuan/ch16_reference_execise_03
[INFO] finished tweaking git repo https://github.com/KarYuKuan/ch16_reference_execise_03
[INFO] tweaked toml for git repo https://github.com/KarYuKuan/ch16_reference_execise_03 written to /workspace/builds/worker-3-tc2/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/KarYuKuan/ch16_reference_execise_03 on toolchain f27166d4c64dc29edc5ea3214357f191edf8b635
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+f27166d4c64dc29edc5ea3214357f191edf8b635" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/KarYuKuan/ch16_reference_execise_03 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" "+f27166d4c64dc29edc5ea3214357f191edf8b635" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+f27166d4c64dc29edc5ea3214357f191edf8b635" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] cde5494ab31a433c72f00591c28a84b24a61fdb64c1532c18d1c52042b4dee54
[INFO] running `Command { std: "docker" "start" "-a" "cde5494ab31a433c72f00591c28a84b24a61fdb64c1532c18d1c52042b4dee54", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "cde5494ab31a433c72f00591c28a84b24a61fdb64c1532c18d1c52042b4dee54", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "cde5494ab31a433c72f00591c28a84b24a61fdb64c1532c18d1c52042b4dee54", kill_on_drop: false }`
[INFO] [stdout] cde5494ab31a433c72f00591c28a84b24a61fdb64c1532c18d1c52042b4dee54
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3-tc2/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@sha256:4848fb76d95f26979359cc7e45710b1dbc8f3acb7aeedee7c460d7702230f228" "/opt/rustwide/cargo-home/bin/cargo" "+f27166d4c64dc29edc5ea3214357f191edf8b635" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 9e396e85cd357c97511fbe7cd6c6fdf271f19d3c1db06cce0d947925a7be2c44
[INFO] running `Command { std: "docker" "start" "-a" "9e396e85cd357c97511fbe7cd6c6fdf271f19d3c1db06cce0d947925a7be2c44", kill_on_drop: false }`
[INFO] [stderr]     Checking ch16_reference_execise_03 v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]  --> src/main.rs:5:9
[INFO] [stdout]   |
[INFO] [stdout] 5 |     let mut s2 = change(&mut s1);
[INFO] [stdout]   |         ----^^
[INFO] [stdout]   |         |
[INFO] [stdout]   |         help: remove this `mut`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_mut)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]  --> src/main.rs:5:9
[INFO] [stdout]   |
[INFO] [stdout] 5 |     let mut s2 = change(&mut s1);
[INFO] [stdout]   |         ----^^
[INFO] [stdout]   |         |
[INFO] [stdout]   |         help: remove this `mut`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_mut)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s2`
[INFO] [stdout]  --> src/main.rs:5:9
[INFO] [stdout]   |
[INFO] [stdout] 5 |     let mut s2 = change(&mut s1);
[INFO] [stdout]   |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_s2`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `s2`
[INFO] [stdout]  --> src/main.rs:5:9
[INFO] [stdout]   |
[INFO] [stdout] 5 |     let mut s2 = change(&mut s1);
[INFO] [stdout]   |         ^^^^^^ help: if this is intentional, prefix it with an underscore: `_s2`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` (part of `#[warn(unused)]`) on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.05s
[INFO] running `Command { std: "docker" "inspect" "9e396e85cd357c97511fbe7cd6c6fdf271f19d3c1db06cce0d947925a7be2c44", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9e396e85cd357c97511fbe7cd6c6fdf271f19d3c1db06cce0d947925a7be2c44", kill_on_drop: false }`
[INFO] [stdout] 9e396e85cd357c97511fbe7cd6c6fdf271f19d3c1db06cce0d947925a7be2c44