[INFO] cloning repository https://github.com/sandyc372/rust-demo
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/sandyc372/rust-demo" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fsandyc372%2Frust-demo", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fsandyc372%2Frust-demo'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 061f80fda67b1ee1ceb42c6a77947afdc9de73bf
[INFO] checking sandyc372/rust-demo against master#84e729a59f216cc64755788a470f165429a731f4 for pr-123737-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fsandyc372%2Frust-demo" "/workspace/builds/worker-0-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-0-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/sandyc372/rust-demo on toolchain 84e729a59f216cc64755788a470f165429a731f4
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+84e729a59f216cc64755788a470f165429a731f4" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/sandyc372/rust-demo
[INFO] finished tweaking git repo https://github.com/sandyc372/rust-demo
[INFO] tweaked toml for git repo https://github.com/sandyc372/rust-demo written to /workspace/builds/worker-0-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/sandyc372/rust-demo 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" "+84e729a59f216cc64755788a470f165429a731f4" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
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[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+84e729a59f216cc64755788a470f165429a731f4" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 36ff714f5e06aae4e5b3743556fc86962114595fd72028ec4cd91c965e4d2707
[INFO] running `Command { std: "docker" "start" "-a" "36ff714f5e06aae4e5b3743556fc86962114595fd72028ec4cd91c965e4d2707", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "36ff714f5e06aae4e5b3743556fc86962114595fd72028ec4cd91c965e4d2707", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "36ff714f5e06aae4e5b3743556fc86962114595fd72028ec4cd91c965e4d2707", kill_on_drop: false }`
[INFO] [stdout] 36ff714f5e06aae4e5b3743556fc86962114595fd72028ec4cd91c965e4d2707
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0-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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+84e729a59f216cc64755788a470f165429a731f4" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 71f402347f93e74e0a851325fe93d8f30cd6f2fdf4f69fead06b3075ea4fb6ba
[INFO] running `Command { std: "docker" "start" "-a" "71f402347f93e74e0a851325fe93d8f30cd6f2fdf4f69fead06b3075ea4fb6ba", kill_on_drop: false }`
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[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/factorial_chains/mod.rs:99:5
[INFO] [stdout]    |
[INFO] [stdout] 99 |     insert(&mut head.as_mut(), new_number);
[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] 99 |     let _ = insert(&mut head.as_mut(), new_number);
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]   --> src/factorial_chains/mod.rs:99:5
[INFO] [stdout]    |
[INFO] [stdout] 99 |     insert(&mut head.as_mut(), new_number);
[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] 99 |     let _ = insert(&mut head.as_mut(), new_number);
[INFO] [stdout]    |     +++++++
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 1m 07s
[INFO] running `Command { std: "docker" "inspect" "71f402347f93e74e0a851325fe93d8f30cd6f2fdf4f69fead06b3075ea4fb6ba", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "71f402347f93e74e0a851325fe93d8f30cd6f2fdf4f69fead06b3075ea4fb6ba", kill_on_drop: false }`
[INFO] [stdout] 71f402347f93e74e0a851325fe93d8f30cd6f2fdf4f69fead06b3075ea4fb6ba