[INFO] fetching crate maybe-single 0.15.0...
[INFO] testing maybe-single-0.15.0 against try#722e1797249a965b6335aebd65d777f917e498f1 for pr-91031
[INFO] extracting crate maybe-single 0.15.0 into /workspace/builds/worker-93/source
[INFO] validating manifest of crates.io crate maybe-single 0.15.0 on toolchain 722e1797249a965b6335aebd65d777f917e498f1
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+722e1797249a965b6335aebd65d777f917e498f1" "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-93/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+722e1797249a965b6335aebd65d777f917e498f1" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+722e1797249a965b6335aebd65d777f917e498f1" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-93/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-93/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" "+722e1797249a965b6335aebd65d777f917e498f1" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 62266c3954e12f24ace074e837711052636af999e865e10a3434903db954e0bb
[INFO] running `Command { std: "docker" "start" "-a" "62266c3954e12f24ace074e837711052636af999e865e10a3434903db954e0bb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "62266c3954e12f24ace074e837711052636af999e865e10a3434903db954e0bb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "62266c3954e12f24ace074e837711052636af999e865e10a3434903db954e0bb", kill_on_drop: false }`
[INFO] [stdout] 62266c3954e12f24ace074e837711052636af999e865e10a3434903db954e0bb
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-93/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-93/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" "+722e1797249a965b6335aebd65d777f917e498f1" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] e6e0b058b1e700ef3f99c45508ece40b9d433f61e7571b56c7c4a61129e0ffba
[INFO] running `Command { std: "docker" "start" "-a" "e6e0b058b1e700ef3f99c45508ece40b9d433f61e7571b56c7c4a61129e0ffba", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.108
[INFO] [stderr]    Compiling parking_lot_core v0.8.5
[INFO] [stderr]    Compiling scopeguard v1.1.0
[INFO] [stderr]    Compiling instant v0.1.12
[INFO] [stderr]    Compiling lock_api v0.4.5
[INFO] [stderr]    Compiling parking_lot v0.11.2
[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 1.50s
[INFO] running `Command { std: "docker" "inspect" "e6e0b058b1e700ef3f99c45508ece40b9d433f61e7571b56c7c4a61129e0ffba", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e6e0b058b1e700ef3f99c45508ece40b9d433f61e7571b56c7c4a61129e0ffba", kill_on_drop: false }`
[INFO] [stdout] e6e0b058b1e700ef3f99c45508ece40b9d433f61e7571b56c7c4a61129e0ffba
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-93/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-93/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" "+722e1797249a965b6335aebd65d777f917e498f1" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 67703e4096e5858bbe4476883e24de64c17ae68b55c2ec789f37244fc9c1aa17
[INFO] running `Command { std: "docker" "start" "-a" "67703e4096e5858bbe4476883e24de64c17ae68b55c2ec789f37244fc9c1aa17", kill_on_drop: false }`
[INFO] [stderr]    Compiling syn v1.0.81
[INFO] [stderr]    Compiling tokio v1.14.0
[INFO] [stderr]    Compiling getrandom v0.2.3
[INFO] [stderr]    Compiling num_cpus v1.13.0
[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 rand_core v0.6.3
[INFO] [stderr]    Compiling rand_chacha v0.3.1
[INFO] [stderr]    Compiling rand v0.8.4
[INFO] [stderr]    Compiling tokio-macros v1.6.0
[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 11.58s
[INFO] running `Command { std: "docker" "inspect" "67703e4096e5858bbe4476883e24de64c17ae68b55c2ec789f37244fc9c1aa17", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "67703e4096e5858bbe4476883e24de64c17ae68b55c2ec789f37244fc9c1aa17", kill_on_drop: false }`
[INFO] [stdout] 67703e4096e5858bbe4476883e24de64c17ae68b55c2ec789f37244fc9c1aa17
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-93/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-93/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" "+722e1797249a965b6335aebd65d777f917e498f1" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] 67035a5e64282c4a4e0fa8db74d2a8898e60ebe2dacefe945bba625aae6d6d77
[INFO] running `Command { std: "docker" "start" "-a" "67035a5e64282c4a4e0fa8db74d2a8898e60ebe2dacefe945bba625aae6d6d77", kill_on_drop: false }`
[INFO] [stdout] 
[INFO] [stdout] running 2 tests
[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 0.05s
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/maybe_single-891b17384b37eca7)
[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 0.38s
[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" "67035a5e64282c4a4e0fa8db74d2a8898e60ebe2dacefe945bba625aae6d6d77", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "67035a5e64282c4a4e0fa8db74d2a8898e60ebe2dacefe945bba625aae6d6d77", kill_on_drop: false }`
[INFO] [stdout] 67035a5e64282c4a4e0fa8db74d2a8898e60ebe2dacefe945bba625aae6d6d77