[INFO] cloning repository https://github.com/shuqiangzhou/rust_study
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/shuqiangzhou/rust_study" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fshuqiangzhou%2Frust_study", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fshuqiangzhou%2Frust_study'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 4fefc8853dfd148d162cb45558e4f3fa90e1293b
[INFO] testing shuqiangzhou/rust_study against master#432e145bd5a974c5b6f4dd9b352891bd7502b69d for pr-87041
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fshuqiangzhou%2Frust_study" "/workspace/builds/worker-15/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-15/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/shuqiangzhou/rust_study on toolchain 432e145bd5a974c5b6f4dd9b352891bd7502b69d
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+432e145bd5a974c5b6f4dd9b352891bd7502b69d" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/shuqiangzhou/rust_study
[INFO] finished tweaking git repo https://github.com/shuqiangzhou/rust_study
[INFO] tweaked toml for git repo https://github.com/shuqiangzhou/rust_study written to /workspace/builds/worker-15/source/Cargo.toml
[INFO] crate git repo https://github.com/shuqiangzhou/rust_study already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+432e145bd5a974c5b6f4dd9b352891bd7502b69d" "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-15/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/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" "+432e145bd5a974c5b6f4dd9b352891bd7502b69d" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 9ded9b84cdb66f7d69ad7c3d7fa5403aa2226474a6e3770803714a22ee1e313b
[INFO] running `Command { std: "docker" "start" "-a" "9ded9b84cdb66f7d69ad7c3d7fa5403aa2226474a6e3770803714a22ee1e313b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "9ded9b84cdb66f7d69ad7c3d7fa5403aa2226474a6e3770803714a22ee1e313b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9ded9b84cdb66f7d69ad7c3d7fa5403aa2226474a6e3770803714a22ee1e313b", kill_on_drop: false }`
[INFO] [stdout] 9ded9b84cdb66f7d69ad7c3d7fa5403aa2226474a6e3770803714a22ee1e313b
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/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" "+432e145bd5a974c5b6f4dd9b352891bd7502b69d" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 2b76141e2fa341ca6cf91fdb23cc0e16930abd96bb278e5d6e0cace6cc7ba99b
[INFO] running `Command { std: "docker" "start" "-a" "2b76141e2fa341ca6cf91fdb23cc0e16930abd96bb278e5d6e0cace6cc7ba99b", 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] [stderr]    Compiling rust_study v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/bin/io.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let mut f = File::open("foo.txt").unwrap();
[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 1.43s
[INFO] running `Command { std: "docker" "inspect" "2b76141e2fa341ca6cf91fdb23cc0e16930abd96bb278e5d6e0cace6cc7ba99b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2b76141e2fa341ca6cf91fdb23cc0e16930abd96bb278e5d6e0cace6cc7ba99b", kill_on_drop: false }`
[INFO] [stdout] 2b76141e2fa341ca6cf91fdb23cc0e16930abd96bb278e5d6e0cace6cc7ba99b
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/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" "+432e145bd5a974c5b6f4dd9b352891bd7502b69d" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 312d349ffd71486741120bbc8ff573a5b8e14af4b0576891a91b6db3391b80a0
[INFO] running `Command { std: "docker" "start" "-a" "312d349ffd71486741120bbc8ff573a5b8e14af4b0576891a91b6db3391b80a0", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling rust_study v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/bin/io.rs:14:9
[INFO] [stdout]    |
[INFO] [stdout] 14 |     let mut f = File::open("foo.txt").unwrap();
[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 test [unoptimized + debuginfo] target(s) in 7.31s
[INFO] running `Command { std: "docker" "inspect" "312d349ffd71486741120bbc8ff573a5b8e14af4b0576891a91b6db3391b80a0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "312d349ffd71486741120bbc8ff573a5b8e14af4b0576891a91b6db3391b80a0", kill_on_drop: false }`
[INFO] [stdout] 312d349ffd71486741120bbc8ff573a5b8e14af4b0576891a91b6db3391b80a0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-15/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" "+432e145bd5a974c5b6f4dd9b352891bd7502b69d" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] 76ae8251d979ff0cc376ea12154cf39b00f01af2e94a9a317fce657e27140efb
[INFO] running `Command { std: "docker" "start" "-a" "76ae8251d979ff0cc376ea12154cf39b00f01af2e94a9a317fce657e27140efb", kill_on_drop: false }`
[INFO] [stdout] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stdout] running 0 tests
[INFO] [stderr]   --> src/bin/io.rs:14:9
[INFO] [stdout] 
[INFO] [stderr]    |
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stderr] 14 |     let mut f = File::open("foo.txt").unwrap();
[INFO] [stdout] 
[INFO] [stderr]    |         ----^
[INFO] [stdout] 
[INFO] [stderr]    |         |
[INFO] [stdout] running 0 tests
[INFO] [stderr]    |         help: remove this `mut`
[INFO] [stdout] 
[INFO] [stderr]    |
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stderr]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stderr] 
[INFO] [stdout] 
[INFO] [stderr] warning: 1 warning emitted
[INFO] [stdout] running 0 tests
[INFO] [stderr] 
[INFO] [stdout] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.01s
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/io-57f80876b2752919)
[INFO] [stdout] 
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/panic-122831b9fc92a4aa)
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/rust_study-32dfcbb50500964a)
[INFO] running `Command { std: "docker" "inspect" "76ae8251d979ff0cc376ea12154cf39b00f01af2e94a9a317fce657e27140efb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "76ae8251d979ff0cc376ea12154cf39b00f01af2e94a9a317fce657e27140efb", kill_on_drop: false }`
[INFO] [stdout] 76ae8251d979ff0cc376ea12154cf39b00f01af2e94a9a317fce657e27140efb