[INFO] cloning repository https://github.com/fahrenkrug/rust_learn_book_collections
[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_collections" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffahrenkrug%2Frust_learn_book_collections", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffahrenkrug%2Frust_learn_book_collections'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 39fa05d9fffbd36a289358263afb7e4aa84b0e19
[INFO] checking fahrenkrug/rust_learn_book_collections against try#45d8b6e68beee1c9c1ce92ae258a7e02f8f13aa4 for pr-83744
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffahrenkrug%2Frust_learn_book_collections" "/workspace/builds/worker-4/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/fahrenkrug/rust_learn_book_collections on toolchain 45d8b6e68beee1c9c1ce92ae258a7e02f8f13aa4
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+45d8b6e68beee1c9c1ce92ae258a7e02f8f13aa4" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/fahrenkrug/rust_learn_book_collections
[INFO] finished tweaking git repo https://github.com/fahrenkrug/rust_learn_book_collections
[INFO] tweaked toml for git repo https://github.com/fahrenkrug/rust_learn_book_collections written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] crate git repo https://github.com/fahrenkrug/rust_learn_book_collections already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+45d8b6e68beee1c9c1ce92ae258a7e02f8f13aa4" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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" "+45d8b6e68beee1c9c1ce92ae258a7e02f8f13aa4" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 1def73790c6bf920dc0a0d98f6b9612f150dfda67ca2a4ed74f07984ffc1e5a0
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "1def73790c6bf920dc0a0d98f6b9612f150dfda67ca2a4ed74f07984ffc1e5a0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "1def73790c6bf920dc0a0d98f6b9612f150dfda67ca2a4ed74f07984ffc1e5a0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1def73790c6bf920dc0a0d98f6b9612f150dfda67ca2a4ed74f07984ffc1e5a0", kill_on_drop: false }`
[INFO] [stdout] 1def73790c6bf920dc0a0d98f6b9612f150dfda67ca2a4ed74f07984ffc1e5a0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4/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" "+45d8b6e68beee1c9c1ce92ae258a7e02f8f13aa4" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 596207aaaebbbdade686d4de44b079d0cf4799d285ef81ca0ec0ce563abc5f84
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "596207aaaebbbdade686d4de44b079d0cf4799d285ef81ca0ec0ce563abc5f84", kill_on_drop: false }`
[INFO] [stderr]     Checking collections v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `does_not_exist`
[INFO] [stdout]   --> src/main.rs:63:9
[INFO] [stdout]    |
[INFO] [stdout] 63 |     let does_not_exist = v.get(100);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_does_not_exist`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/main.rs:101:9
[INFO] [stdout]     |
[INFO] [stdout] 101 |     let mut s = String::new();
[INFO] [stdout]     |         ----^
[INFO] [stdout]     |         |
[INFO] [stdout]     |         help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/main.rs:186:9
[INFO] [stdout]     |
[INFO] [stdout] 186 |     let mut scores: HashMap<_, _> = teams.into_iter().zip(initial_scores.into_iter()).collect();
[INFO] [stdout]     |         ----^^^^^^
[INFO] [stdout]     |         |
[INFO] [stdout]     |         help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `does_not_exist`
[INFO] [stdout]   --> src/main.rs:63:9
[INFO] [stdout]    |
[INFO] [stdout] 63 |     let does_not_exist = v.get(100);
[INFO] [stdout]    |         ^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_does_not_exist`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/main.rs:101:9
[INFO] [stdout]     |
[INFO] [stdout] 101 |     let mut s = String::new();
[INFO] [stdout]     |         ----^
[INFO] [stdout]     |         |
[INFO] [stdout]     |         help: remove this `mut`
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]    --> src/main.rs:186:9
[INFO] [stdout]     |
[INFO] [stdout] 186 |     let mut scores: HashMap<_, _> = teams.into_iter().zip(initial_scores.into_iter()).collect();
[INFO] [stdout]     |         ----^^^^^^
[INFO] [stdout]     |         |
[INFO] [stdout]     |         help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.60s
[INFO] running `Command { std: "docker" "inspect" "596207aaaebbbdade686d4de44b079d0cf4799d285ef81ca0ec0ce563abc5f84", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "596207aaaebbbdade686d4de44b079d0cf4799d285ef81ca0ec0ce563abc5f84", kill_on_drop: false }`
[INFO] [stdout] 596207aaaebbbdade686d4de44b079d0cf4799d285ef81ca0ec0ce563abc5f84