[INFO] fetching crate disjoint-sets 0.4.2...
[INFO] checking disjoint-sets-0.4.2 against try#d990716b6a1fdde1300748828a9c9e79dfd0b898 for pr-74846
[INFO] extracting crate disjoint-sets 0.4.2 into /workspace/builds/worker-6/source
[INFO] validating manifest of crates.io crate disjoint-sets 0.4.2 on toolchain d990716b6a1fdde1300748828a9c9e79dfd0b898
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+d990716b6a1fdde1300748828a9c9e79dfd0b898" "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-6/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+d990716b6a1fdde1300748828a9c9e79dfd0b898" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+d990716b6a1fdde1300748828a9c9e79dfd0b898" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/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:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+d990716b6a1fdde1300748828a9c9e79dfd0b898" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 87ab25c697ea338dc599f82b716be764b2dd562b2c84f155c45a066d554c6dda
[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" "87ab25c697ea338dc599f82b716be764b2dd562b2c84f155c45a066d554c6dda", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "87ab25c697ea338dc599f82b716be764b2dd562b2c84f155c45a066d554c6dda", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "87ab25c697ea338dc599f82b716be764b2dd562b2c84f155c45a066d554c6dda", kill_on_drop: false }`
[INFO] [stdout] 87ab25c697ea338dc599f82b716be764b2dd562b2c84f155c45a066d554c6dda
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/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:a636fd89d022f18117e1dc8fb37a0a009933cdbbe082814857f0e2024962d47c" "/opt/rustwide/cargo-home/bin/cargo" "+d990716b6a1fdde1300748828a9c9e79dfd0b898" "check" "--frozen" "--all" "--all-targets" "--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] 2e59482aaf7cf36dc1b28a5bd77ff27d4506ff1c91c7554b6eb0c7928f0bd435
[INFO] running `Command { std: "docker" "start" "-a" "2e59482aaf7cf36dc1b28a5bd77ff27d4506ff1c91c7554b6eb0c7928f0bd435", kill_on_drop: false }`
[INFO] [stderr]    Compiling serde v1.0.115
[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 v1.0.57
[INFO] [stdout] warning: use of deprecated item '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 10.74s
[INFO] running `Command { std: "docker" "inspect" "2e59482aaf7cf36dc1b28a5bd77ff27d4506ff1c91c7554b6eb0c7928f0bd435", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2e59482aaf7cf36dc1b28a5bd77ff27d4506ff1c91c7554b6eb0c7928f0bd435", kill_on_drop: false }`
[INFO] [stdout] 2e59482aaf7cf36dc1b28a5bd77ff27d4506ff1c91c7554b6eb0c7928f0bd435