[INFO] fetching crate maybe-single 0.14.0...
[INFO] checking maybe-single-0.14.0 against master#836c31742687ba4e2f857b5b698e1e9e6b67619c for pr-81789
[INFO] extracting crate maybe-single 0.14.0 into /workspace/builds/worker-0/source
[INFO] validating manifest of crates.io crate maybe-single 0.14.0 on toolchain 836c31742687ba4e2f857b5b698e1e9e6b67619c
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+836c31742687ba4e2f857b5b698e1e9e6b67619c" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate maybe-single 0.14.0
[INFO] finished tweaking crates.io crate maybe-single 0.14.0
[INFO] tweaked toml for crates.io crate maybe-single 0.14.0 written to /workspace/builds/worker-0/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+836c31742687ba4e2f857b5b698e1e9e6b67619c" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+836c31742687ba4e2f857b5b698e1e9e6b67619c" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+836c31742687ba4e2f857b5b698e1e9e6b67619c" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] e018698fb778407f62b1c9f2b8040ef514bfc366bb9baae2d448d8ba7d818193
[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" "e018698fb778407f62b1c9f2b8040ef514bfc366bb9baae2d448d8ba7d818193", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "e018698fb778407f62b1c9f2b8040ef514bfc366bb9baae2d448d8ba7d818193", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e018698fb778407f62b1c9f2b8040ef514bfc366bb9baae2d448d8ba7d818193", kill_on_drop: false }`
[INFO] [stdout] e018698fb778407f62b1c9f2b8040ef514bfc366bb9baae2d448d8ba7d818193
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-0/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@sha256:20528e8c29e4536546f0102ce88568b16ea7538393a33fcca951030f7af10457" "/opt/rustwide/cargo-home/bin/cargo" "+836c31742687ba4e2f857b5b698e1e9e6b67619c" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 1b4e8fa024efd79250fbb56df41fee97d8ecfcbb7e5d9a1505b37a45872c7c01
[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" "1b4e8fa024efd79250fbb56df41fee97d8ecfcbb7e5d9a1505b37a45872c7c01", kill_on_drop: false }`
[INFO] [stderr]     Checking once_cell v1.7.2
[INFO] [stderr]     Checking instant v0.1.9
[INFO] [stderr]     Checking lock_api v0.4.3
[INFO] [stderr]    Compiling tokio v1.5.0
[INFO] [stderr]     Checking getrandom v0.2.2
[INFO] [stderr]    Compiling syn v1.0.70
[INFO] [stderr]     Checking parking_lot_core v0.8.3
[INFO] [stderr]     Checking rand_core v0.6.2
[INFO] [stderr]     Checking parking_lot v0.11.1
[INFO] [stderr]     Checking rand_chacha v0.3.0
[INFO] [stderr]     Checking maybe-single v0.14.0 (/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 v0.8.3
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling tokio-macros v1.1.0
[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 7.79s
[INFO] running `Command { std: "docker" "inspect" "1b4e8fa024efd79250fbb56df41fee97d8ecfcbb7e5d9a1505b37a45872c7c01", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1b4e8fa024efd79250fbb56df41fee97d8ecfcbb7e5d9a1505b37a45872c7c01", kill_on_drop: false }`
[INFO] [stdout] 1b4e8fa024efd79250fbb56df41fee97d8ecfcbb7e5d9a1505b37a45872c7c01