[INFO] fetching crate maybe-single 0.15.0...
[INFO] checking maybe-single-0.15.0 against master#0599f3403366d9c57f0625e6de3af214b5042a90 for pr-87710
[INFO] extracting crate maybe-single 0.15.0 into /workspace/builds/worker-1/source
[INFO] validating manifest of crates.io crate maybe-single 0.15.0 on toolchain 0599f3403366d9c57f0625e6de3af214b5042a90
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+0599f3403366d9c57f0625e6de3af214b5042a90" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate maybe-single 0.15.0
[INFO] finished tweaking crates.io crate maybe-single 0.15.0
[INFO] tweaked toml for crates.io crate maybe-single 0.15.0 written to /workspace/builds/worker-1/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+0599f3403366d9c57f0625e6de3af214b5042a90" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+0599f3403366d9c57f0625e6de3af214b5042a90" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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" "+0599f3403366d9c57f0625e6de3af214b5042a90" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 0b60a9ef2e43125fa224edf8e2c0d1513a284e293553bd24d44b893262b41874
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "0b60a9ef2e43125fa224edf8e2c0d1513a284e293553bd24d44b893262b41874", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "0b60a9ef2e43125fa224edf8e2c0d1513a284e293553bd24d44b893262b41874", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0b60a9ef2e43125fa224edf8e2c0d1513a284e293553bd24d44b893262b41874", kill_on_drop: false }`
[INFO] [stdout] 0b60a9ef2e43125fa224edf8e2c0d1513a284e293553bd24d44b893262b41874
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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" "+0599f3403366d9c57f0625e6de3af214b5042a90" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 82038f0ca45a18826170da712990e70e0850903dda34d3b3a4234f10d38619a5
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] running `Command { std: "docker" "start" "-a" "82038f0ca45a18826170da712990e70e0850903dda34d3b3a4234f10d38619a5", kill_on_drop: false }`
[INFO] [stderr]    Compiling syn v1.0.75
[INFO] [stderr]     Checking instant v0.1.10
[INFO] [stderr]    Compiling tokio v1.10.1
[INFO] [stderr]     Checking getrandom v0.2.3
[INFO] [stderr]     Checking num_cpus v1.13.0
[INFO] [stderr]     Checking parking_lot_core v0.8.3
[INFO] [stderr]     Checking rand_core v0.6.3
[INFO] [stderr]     Checking parking_lot v0.11.1
[INFO] [stderr]     Checking rand_chacha v0.3.1
[INFO] [stderr]     Checking maybe-single v0.15.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: field is never read: `read_lock`
[INFO] [stdout]   --> src/blocking.rs:73:5
[INFO] [stdout]    |
[INFO] [stdout] 73 |     read_lock: Option<RwLockReadGuard<'a, ()>>,
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `write_lock`
[INFO] [stdout]   --> src/blocking.rs:74:5
[INFO] [stdout]    |
[INFO] [stdout] 74 |     write_lock: Option<RwLockWriteGuard<'a, ()>>,
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Checking rand v0.8.4
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling tokio-macros v1.3.0
[INFO] [stdout] warning: field is never read: `read_lock`
[INFO] [stdout]   --> src/blocking.rs:73:5
[INFO] [stdout]    |
[INFO] [stdout] 73 |     read_lock: Option<RwLockReadGuard<'a, ()>>,
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `write_lock`
[INFO] [stdout]   --> src/blocking.rs:74:5
[INFO] [stdout]    |
[INFO] [stdout] 74 |     write_lock: Option<RwLockWriteGuard<'a, ()>>,
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 10.55s
[INFO] running `Command { std: "docker" "inspect" "82038f0ca45a18826170da712990e70e0850903dda34d3b3a4234f10d38619a5", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "82038f0ca45a18826170da712990e70e0850903dda34d3b3a4234f10d38619a5", kill_on_drop: false }`
[INFO] [stdout] 82038f0ca45a18826170da712990e70e0850903dda34d3b3a4234f10d38619a5