[INFO] fetching crate maybe-single 0.15.0...
[INFO] testing maybe-single-0.15.0 against beta-2021-08-01 for beta-1.55-1
[INFO] extracting crate maybe-single 0.15.0 into /workspace/builds/worker-5/source
[INFO] validating manifest of crates.io crate maybe-single 0.15.0 on toolchain beta-2021-08-01
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-08-01" "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-5/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-08-01" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+beta-2021-08-01" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded rand_core v0.6.3
[INFO] [stderr]   Downloaded pin-project-lite v0.2.7
[INFO] [stderr]   Downloaded event-listener v2.5.1
[INFO] [stderr]   Downloaded lock_api v0.4.4
[INFO] [stderr]   Downloaded tokio-macros v1.3.0
[INFO] [stderr]   Downloaded parking_lot_core v0.8.3
[INFO] [stderr]   Downloaded wasi v0.10.2+wasi-snapshot-preview1
[INFO] [stderr]   Downloaded async-lock v2.4.0
[INFO] [stderr]   Downloaded once_cell v1.8.0
[INFO] [stderr]   Downloaded instant v0.1.10
[INFO] [stderr]   Downloaded redox_syscall v0.2.10
[INFO] [stderr]   Downloaded parking_lot v0.11.1
[INFO] [stderr]   Downloaded rand_chacha v0.3.1
[INFO] [stderr]   Downloaded rand_hc v0.3.1
[INFO] [stderr]   Downloaded rand v0.8.4
[INFO] [stderr]   Downloaded getrandom v0.2.3
[INFO] [stderr]   Downloaded tokio v1.9.0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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" "+beta-2021-08-01" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 8bd786412741830aca4d369e111e7ef7087c47d26165bd581e0298ad48dff0c8
[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" "8bd786412741830aca4d369e111e7ef7087c47d26165bd581e0298ad48dff0c8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "8bd786412741830aca4d369e111e7ef7087c47d26165bd581e0298ad48dff0c8", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8bd786412741830aca4d369e111e7ef7087c47d26165bd581e0298ad48dff0c8", kill_on_drop: false }`
[INFO] [stdout] 8bd786412741830aca4d369e111e7ef7087c47d26165bd581e0298ad48dff0c8
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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=warn" "-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" "+beta-2021-08-01" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 30def28b1b7377c9cd388019a8158e9c0514d231c5b5566ea5b3b36e76be7394
[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" "30def28b1b7377c9cd388019a8158e9c0514d231c5b5566ea5b3b36e76be7394", kill_on_drop: false }`
[INFO] [stderr]    Compiling 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] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 1.14s
[INFO] running `Command { std: "docker" "inspect" "30def28b1b7377c9cd388019a8158e9c0514d231c5b5566ea5b3b36e76be7394", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "30def28b1b7377c9cd388019a8158e9c0514d231c5b5566ea5b3b36e76be7394", kill_on_drop: false }`
[INFO] [stdout] 30def28b1b7377c9cd388019a8158e9c0514d231c5b5566ea5b3b36e76be7394
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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=warn" "-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" "+beta-2021-08-01" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 15a94c958e2b9fb31174fa5c9115a9e423d5eb8f61b15de0b3e5c342a72dd4a2
[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" "15a94c958e2b9fb31174fa5c9115a9e423d5eb8f61b15de0b3e5c342a72dd4a2", kill_on_drop: false }`
[INFO] [stderr]    Compiling tokio v1.9.0
[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]    Compiling 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] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 4.48s
[INFO] running `Command { std: "docker" "inspect" "15a94c958e2b9fb31174fa5c9115a9e423d5eb8f61b15de0b3e5c342a72dd4a2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "15a94c958e2b9fb31174fa5c9115a9e423d5eb8f61b15de0b3e5c342a72dd4a2", kill_on_drop: false }`
[INFO] [stdout] 15a94c958e2b9fb31174fa5c9115a9e423d5eb8f61b15de0b3e5c342a72dd4a2
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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=warn" "-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" "+beta-2021-08-01" "test" "--frozen", kill_on_drop: false }`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 70006010466a854bca504aa6c9ed4bdbdeaf3b052d1015b29e4419aa17e0b673
[INFO] running `Command { std: "docker" "start" "-a" "70006010466a854bca504aa6c9ed4bdbdeaf3b052d1015b29e4419aa17e0b673", kill_on_drop: false }`
[INFO] [stderr] warning: field is never read: `read_lock`
[INFO] [stderr]   --> src/blocking.rs:73:5
[INFO] [stderr]    |
[INFO] [stderr] 73 |     read_lock: Option<RwLockReadGuard<'a, ()>>,
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(dead_code)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: field is never read: `write_lock`
[INFO] [stderr]   --> src/blocking.rs:74:5
[INFO] [stderr]    |
[INFO] [stderr] 74 |     write_lock: Option<RwLockWriteGuard<'a, ()>>,
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: `maybe-single` (lib) generated 2 warnings
[INFO] [stderr] warning: `maybe-single` (lib test) generated 2 warnings (2 duplicates)
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.02s
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/maybe_single-a7a43bc465c0c7f7)
[INFO] [stdout] 
[INFO] [stdout] running 2 tests
[INFO] [stdout] test blocking::test::should_execute_in_parallel ... ok
[INFO] [stdout] test blocking::test::should_execute_serially ... ok
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 2 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.03s
[INFO] [stdout] 
[INFO] [stderr]    Doc-tests maybe-single
[INFO] [stdout] 
[INFO] [stdout] running 0 tests
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "70006010466a854bca504aa6c9ed4bdbdeaf3b052d1015b29e4419aa17e0b673", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "70006010466a854bca504aa6c9ed4bdbdeaf3b052d1015b29e4419aa17e0b673", kill_on_drop: false }`
[INFO] [stdout] 70006010466a854bca504aa6c9ed4bdbdeaf3b052d1015b29e4419aa17e0b673
