[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 master#a77da2d454e6caa227a85b16410b95f93495e7e0 for pr-91031
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fjmacmahon%2Frust-playground" "/workspace/builds/worker-70/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-70/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/jmacmahon/rust-playground on toolchain a77da2d454e6caa227a85b16410b95f93495e7e0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+a77da2d454e6caa227a85b16410b95f93495e7e0" "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-70/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" "+a77da2d454e6caa227a85b16410b95f93495e7e0" "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-70/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-70/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@sha256:5736fa189c1c60b01babf4b8b698fe57b6ecc41933a7ff2e0b8d7a221459412b" "/opt/rustwide/cargo-home/bin/cargo" "+a77da2d454e6caa227a85b16410b95f93495e7e0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 88a82c27cd8074ed0177c974a31c196947ffc18f046386804536394b966e5434
[INFO] running `Command { std: "docker" "start" "-a" "88a82c27cd8074ed0177c974a31c196947ffc18f046386804536394b966e5434", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "88a82c27cd8074ed0177c974a31c196947ffc18f046386804536394b966e5434", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "88a82c27cd8074ed0177c974a31c196947ffc18f046386804536394b966e5434", kill_on_drop: false }`
[INFO] [stdout] 88a82c27cd8074ed0177c974a31c196947ffc18f046386804536394b966e5434
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-70/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-70/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@sha256:5736fa189c1c60b01babf4b8b698fe57b6ecc41933a7ff2e0b8d7a221459412b" "/opt/rustwide/cargo-home/bin/cargo" "+a77da2d454e6caa227a85b16410b95f93495e7e0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] f3189a80df3b80c99c68cde2e583e73bbe961d0b849557b519c9c6be3049358f
[INFO] running `Command { std: "docker" "start" "-a" "f3189a80df3b80c99c68cde2e583e73bbe961d0b849557b519c9c6be3049358f", 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" "f3189a80df3b80c99c68cde2e583e73bbe961d0b849557b519c9c6be3049358f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f3189a80df3b80c99c68cde2e583e73bbe961d0b849557b519c9c6be3049358f", kill_on_drop: false }`
[INFO] [stdout] f3189a80df3b80c99c68cde2e583e73bbe961d0b849557b519c9c6be3049358f