[INFO] cloning repository https://github.com/fteychene/rust-error-playground
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/fteychene/rust-error-playground" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffteychene%2Frust-error-playground", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffteychene%2Frust-error-playground'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] fa8ce5306515ca1d2c77d022d760ab7c00360f86
[INFO] checking fteychene/rust-error-playground against master#dfd7b8d03fb93d0e03147d28b3be6d93260fa94d for pr-87050
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Ffteychene%2Frust-error-playground" "/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/fteychene/rust-error-playground on toolchain dfd7b8d03fb93d0e03147d28b3be6d93260fa94d
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+dfd7b8d03fb93d0e03147d28b3be6d93260fa94d" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/fteychene/rust-error-playground
[INFO] finished tweaking git repo https://github.com/fteychene/rust-error-playground
[INFO] tweaked toml for git repo https://github.com/fteychene/rust-error-playground written to /workspace/builds/worker-4/source/Cargo.toml
[INFO] crate git repo https://github.com/fteychene/rust-error-playground already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+dfd7b8d03fb93d0e03147d28b3be6d93260fa94d" "fetch" "--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@sha256:34b6a614d2c27851fe6cbf88fbd1137609cefab8b10d0615aaeb6fd47975d74e" "/opt/rustwide/cargo-home/bin/cargo" "+dfd7b8d03fb93d0e03147d28b3be6d93260fa94d" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 1756943a86ad6f0c9ff079ccfa11a9de81527c62afd50ffb2da045ee0f5bbc28
[INFO] running `Command { std: "docker" "start" "-a" "1756943a86ad6f0c9ff079ccfa11a9de81527c62afd50ffb2da045ee0f5bbc28", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "1756943a86ad6f0c9ff079ccfa11a9de81527c62afd50ffb2da045ee0f5bbc28", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1756943a86ad6f0c9ff079ccfa11a9de81527c62afd50ffb2da045ee0f5bbc28", kill_on_drop: false }`
[INFO] [stdout] 1756943a86ad6f0c9ff079ccfa11a9de81527c62afd50ffb2da045ee0f5bbc28
[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@sha256:34b6a614d2c27851fe6cbf88fbd1137609cefab8b10d0615aaeb6fd47975d74e" "/opt/rustwide/cargo-home/bin/cargo" "+dfd7b8d03fb93d0e03147d28b3be6d93260fa94d" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 0b78660d46dff05c5d3fd61d87950d999843bbf505c9912e40b572a65d17f561
[INFO] running `Command { std: "docker" "start" "-a" "0b78660d46dff05c5d3fd61d87950d999843bbf505c9912e40b572a65d17f561", kill_on_drop: false }`
[INFO] [stderr]    Compiling memchr v2.2.1
[INFO] [stderr]     Checking regex-syntax v0.6.12
[INFO] [stderr]     Checking thread_local v0.3.6
[INFO] [stderr]     Checking aho-corasick v0.7.6
[INFO] [stderr]     Checking regex v1.3.1
[INFO] [stderr]     Checking vanilla v0.1.0 (/opt/rustwide/workdir/vanilla)
[INFO] [stderr]     Checking vanillacustom v0.1.0 (/opt/rustwide/workdir/vanillacustom)
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> vanilla/src/main.rs:34:18
[INFO] [stdout]    |
[INFO] [stdout] 34 | fn remove_header(mut chapters: Vec<String>) -> Result<Vec<String>, Box<dyn Error>> {
[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: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> vanilla/src/main.rs:34:18
[INFO] [stdout]    |
[INFO] [stdout] 34 | fn remove_header(mut chapters: Vec<String>) -> Result<Vec<String>, Box<dyn Error>> {
[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: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 8.67s
[INFO] running `Command { std: "docker" "inspect" "0b78660d46dff05c5d3fd61d87950d999843bbf505c9912e40b572a65d17f561", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0b78660d46dff05c5d3fd61d87950d999843bbf505c9912e40b572a65d17f561", kill_on_drop: false }`
[INFO] [stdout] 0b78660d46dff05c5d3fd61d87950d999843bbf505c9912e40b572a65d17f561