[INFO] updating cached repository https://github.com/matklad/group-by-challenge
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "-c" "remote.origin.fetch=refs/heads/*:refs/heads/*" "fetch" "origin" "--force" "--prune", kill_on_drop: false }`
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 297c95d461427a61f621767443897c37bef43f0f
[INFO] checking matklad/group-by-challenge against try#22dd2dd1dc07f63ae9394352d412f020d2985684 for pr-74627
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmatklad%2Fgroup-by-challenge" "/workspace/builds/worker-7/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-7/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/matklad/group-by-challenge on toolchain 22dd2dd1dc07f63ae9394352d412f020d2985684
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+22dd2dd1dc07f63ae9394352d412f020d2985684" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/matklad/group-by-challenge
[INFO] finished tweaking git repo https://github.com/matklad/group-by-challenge
[INFO] tweaked toml for git repo https://github.com/matklad/group-by-challenge written to /workspace/builds/worker-7/source/Cargo.toml
[INFO] crate git repo https://github.com/matklad/group-by-challenge already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+22dd2dd1dc07f63ae9394352d412f020d2985684" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+22dd2dd1dc07f63ae9394352d412f020d2985684" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 06851e8ee1bcb5dbb60995dc9c43013120aff34a83ac5e30e666ba34551d2e32
[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" "06851e8ee1bcb5dbb60995dc9c43013120aff34a83ac5e30e666ba34551d2e32", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "06851e8ee1bcb5dbb60995dc9c43013120aff34a83ac5e30e666ba34551d2e32", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "06851e8ee1bcb5dbb60995dc9c43013120aff34a83ac5e30e666ba34551d2e32", kill_on_drop: false }`
[INFO] [stdout] 06851e8ee1bcb5dbb60995dc9c43013120aff34a83ac5e30e666ba34551d2e32
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+22dd2dd1dc07f63ae9394352d412f020d2985684" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] b9106481edeee22253d85b0cead3a8dbcbc624ab8abf483a668b5d9a1be61840
[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" "b9106481edeee22253d85b0cead3a8dbcbc624ab8abf483a668b5d9a1be61840", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Checking group-by-challenge v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `xs`
[INFO] [stdout]  --> src/lib.rs:1:29
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn group_by<I, F, K, T>(xs: I, key_fn: F) -> Vec<(K, Vec<T>)>
[INFO] [stdout]   |                             ^^ help: if this is intentional, prefix it with an underscore: `_xs`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `key_fn`
[INFO] [stdout]  --> src/lib.rs:1:36
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn group_by<I, F, K, T>(xs: I, key_fn: F) -> Vec<(K, Vec<T>)>
[INFO] [stdout]   |                                    ^^^^^^ help: if this is intentional, prefix it with an underscore: `_key_fn`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `xs`
[INFO] [stdout]  --> src/lib.rs:1:29
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn group_by<I, F, K, T>(xs: I, key_fn: F) -> Vec<(K, Vec<T>)>
[INFO] [stdout]   |                             ^^ help: if this is intentional, prefix it with an underscore: `_xs`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `key_fn`
[INFO] [stdout]  --> src/lib.rs:1:36
[INFO] [stdout]   |
[INFO] [stdout] 1 | pub fn group_by<I, F, K, T>(xs: I, key_fn: F) -> Vec<(K, Vec<T>)>
[INFO] [stdout]   |                                    ^^^^^^ help: if this is intentional, prefix it with an underscore: `_key_fn`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.45s
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "b9106481edeee22253d85b0cead3a8dbcbc624ab8abf483a668b5d9a1be61840", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "b9106481edeee22253d85b0cead3a8dbcbc624ab8abf483a668b5d9a1be61840", kill_on_drop: false }`
[INFO] [stdout] b9106481edeee22253d85b0cead3a8dbcbc624ab8abf483a668b5d9a1be61840