[INFO] cloning repository https://github.com/drewwyatt/card-flipping
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/drewwyatt/card-flipping" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fdrewwyatt%2Fcard-flipping", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fdrewwyatt%2Fcard-flipping'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 2269809d6924662b35097afb72a5f96a637a326c
[INFO] testing drewwyatt/card-flipping against master#a77da2d454e6caa227a85b16410b95f93495e7e0 for pr-91031
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fdrewwyatt%2Fcard-flipping" "/workspace/builds/worker-56/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-56/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/drewwyatt/card-flipping 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/drewwyatt/card-flipping
[INFO] finished tweaking git repo https://github.com/drewwyatt/card-flipping
[INFO] tweaked toml for git repo https://github.com/drewwyatt/card-flipping written to /workspace/builds/worker-56/source/Cargo.toml
[INFO] crate git repo https://github.com/drewwyatt/card-flipping 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-56/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-56/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] 47ba5317d195da7b5c276d40ab990eb9285886464a35930e82c702af275592e4
[INFO] running `Command { std: "docker" "start" "-a" "47ba5317d195da7b5c276d40ab990eb9285886464a35930e82c702af275592e4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "47ba5317d195da7b5c276d40ab990eb9285886464a35930e82c702af275592e4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "47ba5317d195da7b5c276d40ab990eb9285886464a35930e82c702af275592e4", kill_on_drop: false }`
[INFO] [stdout] 47ba5317d195da7b5c276d40ab990eb9285886464a35930e82c702af275592e4
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-56/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-56/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] 8d19324b0f7c608a20d6b68c4aa97cfb0bfa980d66dbd008e5154f322d545d2f
[INFO] running `Command { std: "docker" "start" "-a" "8d19324b0f7c608a20d6b68c4aa97cfb0bfa980d66dbd008e5154f322d545d2f", kill_on_drop: false }`
[INFO] [stderr]    Compiling card-flipping v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused variable: `card`
[INFO] [stdout]   --> src/lib/models.rs:36:24
[INFO] [stdout]    |
[INFO] [stdout] 36 |     fn flip(&mut self, card: Option<&Card>) {
[INFO] [stdout]    |                        ^^^^ help: if this is intentional, prefix it with an underscore: `_card`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0502]: cannot borrow `*self` as mutable because it is also borrowed as immutable
[INFO] [stdout]   --> src/lib/models.rs:26:17
[INFO] [stdout]    |
[INFO] [stdout] 26 |                 self.flip(self.cards.get(idx - 1));
[INFO] [stdout]    |                 ^^^^^----^-----------------------^
[INFO] [stdout]    |                 |    |    |
[INFO] [stdout]    |                 |    |    immutable borrow occurs here
[INFO] [stdout]    |                 |    immutable borrow later used by call
[INFO] [stdout]    |                 mutable borrow occurs here
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error[E0502]: cannot borrow `*self` as mutable because it is also borrowed as immutable
[INFO] [stdout]   --> src/lib/models.rs:27:17
[INFO] [stdout]    |
[INFO] [stdout] 27 |                 self.flip(self.cards.get(idx + 1));
[INFO] [stdout]    |                 ^^^^^----^-----------------------^
[INFO] [stdout]    |                 |    |    |
[INFO] [stdout]    |                 |    |    immutable borrow occurs here
[INFO] [stdout]    |                 |    immutable borrow later used by call
[INFO] [stdout]    |                 mutable borrow occurs here
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to 2 previous errors; 1 warning 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 `card-flipping` due to 3 previous errors; 1 warning emitted
[INFO] running `Command { std: "docker" "inspect" "8d19324b0f7c608a20d6b68c4aa97cfb0bfa980d66dbd008e5154f322d545d2f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8d19324b0f7c608a20d6b68c4aa97cfb0bfa980d66dbd008e5154f322d545d2f", kill_on_drop: false }`
[INFO] [stdout] 8d19324b0f7c608a20d6b68c4aa97cfb0bfa980d66dbd008e5154f322d545d2f