[INFO] fetching crate async-option 0.1.1...
[INFO] testing async-option-0.1.1 against master#62efba8a050c64249dab942951bb28f710208bc8 for pr-90799
[INFO] extracting crate async-option 0.1.1 into /workspace/builds/worker-3/source
[INFO] validating manifest of crates.io crate async-option 0.1.1 on toolchain 62efba8a050c64249dab942951bb28f710208bc8
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate async-option 0.1.1
[INFO] finished tweaking crates.io crate async-option 0.1.1
[INFO] tweaked toml for crates.io crate async-option 0.1.1 written to /workspace/builds/worker-3/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+62efba8a050c64249dab942951bb28f710208bc8" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "+62efba8a050c64249dab942951bb28f710208bc8" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 2d1d18b3103c1c00fdf7140491124ceff949ca741f275c49c50b23b5cffd355e
[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" "2d1d18b3103c1c00fdf7140491124ceff949ca741f275c49c50b23b5cffd355e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "2d1d18b3103c1c00fdf7140491124ceff949ca741f275c49c50b23b5cffd355e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2d1d18b3103c1c00fdf7140491124ceff949ca741f275c49c50b23b5cffd355e", kill_on_drop: false }`
[INFO] [stdout] 2d1d18b3103c1c00fdf7140491124ceff949ca741f275c49c50b23b5cffd355e
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "+62efba8a050c64249dab942951bb28f710208bc8" "build" "--frozen" "--message-format=json", 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] a8656bbf9864434558d1e2fb986294f9644a5f273d547f23a442660a4da88f60
[INFO] running `Command { std: "docker" "start" "-a" "a8656bbf9864434558d1e2fb986294f9644a5f273d547f23a442660a4da88f60", kill_on_drop: false }`
[INFO] [stderr]    Compiling async-option v0.1.1 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/lib.rs:96:17
[INFO] [stdout]    |
[INFO] [stdout] 96 |                 mem::replace(self, CellValue::Fin(None));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.30s
[INFO] running `Command { std: "docker" "inspect" "a8656bbf9864434558d1e2fb986294f9644a5f273d547f23a442660a4da88f60", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "a8656bbf9864434558d1e2fb986294f9644a5f273d547f23a442660a4da88f60", kill_on_drop: false }`
[INFO] [stdout] a8656bbf9864434558d1e2fb986294f9644a5f273d547f23a442660a4da88f60
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-3/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" "+62efba8a050c64249dab942951bb28f710208bc8" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 7e1f37fad4033c320047a0168f2e52c123ea7c38548b79ffe6204814acfac893
[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" "7e1f37fad4033c320047a0168f2e52c123ea7c38548b79ffe6204814acfac893", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling autocfg v1.0.1
[INFO] [stderr]    Compiling cfg-if v0.1.10
[INFO] [stderr]    Compiling libc v0.2.108
[INFO] [stderr]    Compiling lazy_static v1.4.0
[INFO] [stderr]    Compiling log v0.4.14
[INFO] [stderr]    Compiling cfg-if v1.0.0
[INFO] [stderr]    Compiling scopeguard v1.1.0
[INFO] [stderr]    Compiling slab v0.4.5
[INFO] [stderr]    Compiling byteorder v1.4.3
[INFO] [stderr]    Compiling tokio-mock-task v0.1.1
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/lib.rs:96:17
[INFO] [stdout]    |
[INFO] [stdout] 96 |                 mem::replace(self, CellValue::Fin(None));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling lock_api v0.3.4
[INFO] [stderr]    Compiling crossbeam-utils v0.7.2
[INFO] [stderr]    Compiling memoffset v0.5.6
[INFO] [stderr]    Compiling crossbeam-epoch v0.8.2
[INFO] [stderr]    Compiling iovec v0.1.4
[INFO] [stderr]    Compiling num_cpus v1.13.0
[INFO] [stderr]    Compiling net2 v0.2.37
[INFO] [stderr]    Compiling parking_lot_core v0.6.2
[INFO] [stderr]    Compiling bytes v0.4.12
[INFO] [stderr]    Compiling parking_lot v0.9.0
[INFO] [stderr]    Compiling tokio-executor v0.1.10
[INFO] [stderr]    Compiling crossbeam-queue v0.2.3
[INFO] [stderr]    Compiling mio v0.6.23
[INFO] [stderr]    Compiling tokio-io v0.1.13
[INFO] [stderr]    Compiling tokio-timer v0.2.13
[INFO] [stderr]    Compiling tokio-current-thread v0.1.7
[INFO] [stderr]    Compiling crossbeam-deque v0.7.4
[INFO] [stderr]    Compiling tokio-threadpool v0.1.18
[INFO] [stderr]    Compiling tokio-codec v0.1.2
[INFO] [stderr]    Compiling tokio-reactor v0.1.12
[INFO] [stderr]    Compiling mio-uds v0.6.8
[INFO] [stderr]    Compiling tokio-uds v0.2.7
[INFO] [stderr]    Compiling tokio-tcp v0.1.4
[INFO] [stderr]    Compiling tokio-udp v0.1.6
[INFO] [stderr]    Compiling tokio-fs v0.1.7
[INFO] [stderr]    Compiling tokio v0.1.22
[INFO] [stderr]    Compiling async-option v0.1.1 (/opt/rustwide/workdir)
[INFO] [stdout] error: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]   --> src/lib.rs:96:17
[INFO] [stdout]    |
[INFO] [stdout] 96 |                 mem::replace(self, CellValue::Fin(None));
[INFO] [stdout]    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout] note: the lint level is defined here
[INFO] [stdout]   --> src/lib.rs:26:24
[INFO] [stdout]    |
[INFO] [stdout] 26 | #![cfg_attr(test, deny(warnings))]
[INFO] [stdout]    |                        ^^^^^^^^
[INFO] [stdout]    = note: `#[deny(unused_must_use)]` implied by `#[deny(warnings)]`
[INFO] [stdout]    = note: if you don't need the old value, you can just assign the new value directly
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `async-option` due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "7e1f37fad4033c320047a0168f2e52c123ea7c38548b79ffe6204814acfac893", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7e1f37fad4033c320047a0168f2e52c123ea7c38548b79ffe6204814acfac893", kill_on_drop: false }`
[INFO] [stdout] 7e1f37fad4033c320047a0168f2e52c123ea7c38548b79ffe6204814acfac893