[INFO] fetching crate disjoint-sets 0.4.2...
[INFO] checking disjoint-sets-0.4.2 against try#f47dd4da3ae8c32c9e65d307bfe640b143e674df for pr-77526
[INFO] extracting crate disjoint-sets 0.4.2 into /workspace/builds/worker-8/source
[INFO] validating manifest of crates.io crate disjoint-sets 0.4.2 on toolchain f47dd4da3ae8c32c9e65d307bfe640b143e674df
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate disjoint-sets 0.4.2
[INFO] finished tweaking crates.io crate disjoint-sets 0.4.2
[INFO] tweaked toml for crates.io crate disjoint-sets 0.4.2 written to /workspace/builds/worker-8/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-8/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-8/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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 2bf8c533ab3c63e2af06446d55628ff084b44600c32cab0bf00c14a8f8d7786b
[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" "2bf8c533ab3c63e2af06446d55628ff084b44600c32cab0bf00c14a8f8d7786b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "2bf8c533ab3c63e2af06446d55628ff084b44600c32cab0bf00c14a8f8d7786b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2bf8c533ab3c63e2af06446d55628ff084b44600c32cab0bf00c14a8f8d7786b", kill_on_drop: false }`
[INFO] [stdout] 2bf8c533ab3c63e2af06446d55628ff084b44600c32cab0bf00c14a8f8d7786b
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-8/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-8/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" "rustops/crates-build-env@sha256:d92eaeed33fa75130ca1ee6c8a01d1ffb62bac859dfdfb3450e3e5d1c0146529" "/opt/rustwide/cargo-home/bin/cargo" "+f47dd4da3ae8c32c9e65d307bfe640b143e674df" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 7b38d48678f8ca2df669688700542d8c16e292b13612bb074eaf049f9e3227cb
[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" "7b38d48678f8ca2df669688700542d8c16e292b13612bb074eaf049f9e3227cb", kill_on_drop: false }`
[INFO] [stderr]    Compiling serde v1.0.116
[INFO] [stderr]     Checking itoa v0.4.6
[INFO] [stderr]     Checking disjoint-sets v0.4.2 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/tree.rs:465:17
[INFO] [stdout]     |
[INFO] [stdout] 465 | /                 mem::replace(&mut *guard_parent, Root {
[INFO] [stdout] 466 | |                     data: new_data,
[INFO] [stdout] 467 | |                     rank: rank,
[INFO] [stdout] 468 | |                 });
[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]     Checking serde_json v1.0.58
[INFO] [stdout] warning: use of deprecated macro `try`: use the `?` operator instead
[INFO] [stdout]    --> src/tree.rs:668:17
[INFO] [stdout]     |
[INFO] [stdout] 668 |                 try!(self.unify(v1, v2));
[INFO] [stdout]     |                 ^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: `#[warn(deprecated)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused return value of `std::mem::replace` that must be used
[INFO] [stdout]    --> src/tree.rs:465:17
[INFO] [stdout]     |
[INFO] [stdout] 465 | /                 mem::replace(&mut *guard_parent, Root {
[INFO] [stdout] 466 | |                     data: new_data,
[INFO] [stdout] 467 | |                     rank: rank,
[INFO] [stdout] 468 | |                 });
[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: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 11.50s
[INFO] running `Command { std: "docker" "inspect" "7b38d48678f8ca2df669688700542d8c16e292b13612bb074eaf049f9e3227cb", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7b38d48678f8ca2df669688700542d8c16e292b13612bb074eaf049f9e3227cb", kill_on_drop: false }`
[INFO] [stdout] 7b38d48678f8ca2df669688700542d8c16e292b13612bb074eaf049f9e3227cb