[INFO] cloning repository https://github.com/jmacmahon/rust-playground
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/jmacmahon/rust-playground" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjmacmahon%2Frust-playground", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjmacmahon%2Frust-playground'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] d3ad60100e7e7cc92aa7af86552948d100656ef3
[INFO] testing jmacmahon/rust-playground against 1.60.0 for beta-1.61-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjmacmahon%2Frust-playground" "/workspace/builds/worker-20/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-20/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/jmacmahon/rust-playground on toolchain 1.60.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.60.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/jmacmahon/rust-playground
[INFO] finished tweaking git repo https://github.com/jmacmahon/rust-playground
[INFO] tweaked toml for git repo https://github.com/jmacmahon/rust-playground written to /workspace/builds/worker-20/source/Cargo.toml
[INFO] crate git repo https://github.com/jmacmahon/rust-playground already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.60.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-20/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-20/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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+1.60.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 6395d3039fbec88ed1f74e13ee8f28865c051dc0a6bdebf7dd2b39a914fe292c
[INFO] running `Command { std: "docker" "start" "-a" "6395d3039fbec88ed1f74e13ee8f28865c051dc0a6bdebf7dd2b39a914fe292c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "6395d3039fbec88ed1f74e13ee8f28865c051dc0a6bdebf7dd2b39a914fe292c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "6395d3039fbec88ed1f74e13ee8f28865c051dc0a6bdebf7dd2b39a914fe292c", kill_on_drop: false }`
[INFO] [stdout] 6395d3039fbec88ed1f74e13ee8f28865c051dc0a6bdebf7dd2b39a914fe292c
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-20/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-20/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=warn" "-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:b0c94ce3c1162fcb8e57cac5b65ec2f72eabb1eebea4fcc35e269e823f681646" "/opt/rustwide/cargo-home/bin/cargo" "+1.60.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 2c256af72c83682208504b1342b4373f62cab875d9dc585cd83229021a8302cb
[INFO] running `Command { std: "docker" "start" "-a" "2c256af72c83682208504b1342b4373f62cab875d9dc585cd83229021a8302cb", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling scratch v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `z`
[INFO] [stdout]  --> src/main.rs:4:9
[INFO] [stdout]   |
[INFO] [stdout] 4 |     let z = &x;
[INFO] [stdout]   |         ^ help: if this is intentional, prefix it with an underscore: `_z`
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `x`
[INFO] [stdout]   --> src/main.rs:12:10
[INFO] [stdout]    |
[INFO] [stdout] 12 | fn test2(x: &i32) -> () {
[INFO] [stdout]    |          ^ help: if this is intentional, prefix it with an underscore: `_x`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0502]: cannot borrow `x` as immutable because it is also borrowed as mutable
[INFO] [stdout]  --> src/main.rs:4:13
[INFO] [stdout]   |
[INFO] [stdout] 3 |     let y = &mut x;
[INFO] [stdout]   |             ------ mutable borrow occurs here
[INFO] [stdout] 4 |     let z = &x;
[INFO] [stdout]   |             ^^ immutable borrow occurs here
[INFO] [stdout] 5 |     println!("{:?}", y);
[INFO] [stdout]   |                      - mutable borrow later used here
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error; 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0502`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `scratch` due to 2 previous errors; 2 warnings emitted
[INFO] running `Command { std: "docker" "inspect" "2c256af72c83682208504b1342b4373f62cab875d9dc585cd83229021a8302cb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2c256af72c83682208504b1342b4373f62cab875d9dc585cd83229021a8302cb", kill_on_drop: false }`
[INFO] [stdout] 2c256af72c83682208504b1342b4373f62cab875d9dc585cd83229021a8302cb