[INFO] cloning repository https://github.com/chakru-hero/RustPlayground
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/chakru-hero/RustPlayground" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fchakru-hero%2FRustPlayground", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fchakru-hero%2FRustPlayground'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 2eb8bcdf3ac22759089645f50ccae1ab8175cdae
[INFO] checking chakru-hero/RustPlayground against master#9748d87dc70a9a6725c5dbd76ce29d04752b4f90 for pr-144156
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fchakru-hero%2FRustPlayground" "/workspace/builds/worker-4-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-4-tc1/source'...
[INFO] [stderr] done.
[INFO] started tweaking git repo https://github.com/chakru-hero/RustPlayground
[INFO] finished tweaking git repo https://github.com/chakru-hero/RustPlayground
[INFO] tweaked toml for git repo https://github.com/chakru-hero/RustPlayground written to /workspace/builds/worker-4-tc1/source/Cargo.toml
[INFO] validating manifest of git repo https://github.com/chakru-hero/RustPlayground on toolchain 9748d87dc70a9a6725c5dbd76ce29d04752b4f90
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+9748d87dc70a9a6725c5dbd76ce29d04752b4f90" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate git repo https://github.com/chakru-hero/RustPlayground 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" "+9748d87dc70a9a6725c5dbd76ce29d04752b4f90" "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-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-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:cf8efcab8866f2cf4285301c7418e2f4f2a9b088c91ba69c40d5b659f81557f7" "/opt/rustwide/cargo-home/bin/cargo" "+9748d87dc70a9a6725c5dbd76ce29d04752b4f90" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] aeb8ee9a75e6f8aebbe65674cb9ba599d0521c0fe569f4dc3973349354b8f538
[INFO] running `Command { std: "docker" "start" "-a" "aeb8ee9a75e6f8aebbe65674cb9ba599d0521c0fe569f4dc3973349354b8f538", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "aeb8ee9a75e6f8aebbe65674cb9ba599d0521c0fe569f4dc3973349354b8f538", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "aeb8ee9a75e6f8aebbe65674cb9ba599d0521c0fe569f4dc3973349354b8f538", kill_on_drop: false }`
[INFO] [stdout] aeb8ee9a75e6f8aebbe65674cb9ba599d0521c0fe569f4dc3973349354b8f538
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-4-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:cf8efcab8866f2cf4285301c7418e2f4f2a9b088c91ba69c40d5b659f81557f7" "/opt/rustwide/cargo-home/bin/cargo" "+9748d87dc70a9a6725c5dbd76ce29d04752b4f90" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 6e0aec71042e3ab1f8249abd153d6cd951e409a866913c9b546d8dbf0c14c82a
[INFO] running `Command { std: "docker" "start" "-a" "6e0aec71042e3ab1f8249abd153d6cd951e409a866913c9b546d8dbf0c14c82a", kill_on_drop: false }`
[INFO] [stderr]     Checking playground v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/main.rs:22:8
[INFO] [stdout]    |
[INFO] [stdout] 22 |    let mut y : i32 = 11;
[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:22:8
[INFO] [stdout]    |
[INFO] [stdout] 22 |    let mut y : i32 = 11;
[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] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.12s
[INFO] running `Command { std: "docker" "inspect" "6e0aec71042e3ab1f8249abd153d6cd951e409a866913c9b546d8dbf0c14c82a", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6e0aec71042e3ab1f8249abd153d6cd951e409a866913c9b546d8dbf0c14c82a", kill_on_drop: false }`
[INFO] [stdout] 6e0aec71042e3ab1f8249abd153d6cd951e409a866913c9b546d8dbf0c14c82a