[INFO] fetching crate disjoint-set 0.0.2...
[INFO] testing disjoint-set-0.0.2 against 1.69.0 for beta-1.70-1
[INFO] extracting crate disjoint-set 0.0.2 into /workspace/builds/worker-5-tc1/source
[INFO] validating manifest of crates.io crate disjoint-set 0.0.2 on toolchain 1.69.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.69.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking crates.io crate disjoint-set 0.0.2
[INFO] finished tweaking crates.io crate disjoint-set 0.0.2
[INFO] tweaked toml for crates.io crate disjoint-set 0.0.2 written to /workspace/builds/worker-5-tc1/source/Cargo.toml
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" __CARGO_TEST_CHANNEL_OVERRIDE_DO_NOT_USE_THIS="nightly" "/workspace/cargo-home/bin/cargo" "+1.69.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.69.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc1/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@sha256:5ff2268d62e97bff2cde7d5815dd6ed5b47097566f13b8d0ca110b04b60e07ed" "/opt/rustwide/cargo-home/bin/cargo" "+1.69.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 7a6d33332bda60e60be19e501b27b0237fe78e6cc9366ea5297ee1a2308ccacc
[INFO] running `Command { std: "docker" "start" "-a" "7a6d33332bda60e60be19e501b27b0237fe78e6cc9366ea5297ee1a2308ccacc", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "7a6d33332bda60e60be19e501b27b0237fe78e6cc9366ea5297ee1a2308ccacc", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "7a6d33332bda60e60be19e501b27b0237fe78e6cc9366ea5297ee1a2308ccacc", kill_on_drop: false }`
[INFO] [stdout] 7a6d33332bda60e60be19e501b27b0237fe78e6cc9366ea5297ee1a2308ccacc
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc1/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" "RUSTDOCFLAGS=--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@sha256:5ff2268d62e97bff2cde7d5815dd6ed5b47097566f13b8d0ca110b04b60e07ed" "/opt/rustwide/cargo-home/bin/cargo" "+1.69.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 9e4b4e92372eaf306c552a2282dd30e83c4b0ddee3a589a4ee4825fe6adff2db
[INFO] running `Command { std: "docker" "start" "-a" "9e4b4e92372eaf306c552a2282dd30e83c4b0ddee3a589a4ee4825fe6adff2db", kill_on_drop: false }`
[INFO] [stderr]    Compiling disjoint-set v0.0.2 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `std::rc::Rc`
[INFO] [stdout]  --> src/lib.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use std::rc::Rc;
[INFO] [stdout]   |     ^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `p`
[INFO] [stdout]   --> src/lib.rs:37:18
[INFO] [stdout]    |
[INFO] [stdout] 37 |             Some(p) => return,
[INFO] [stdout]    |                  ^ help: if this is intentional, prefix it with an underscore: `_p`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/lib.rs:35:13
[INFO] [stdout]    |
[INFO] [stdout] 35 |         let mut len = &mut self.set_size;
[INFO] [stdout]    |             ----^^^
[INFO] [stdout]    |             |
[INFO] [stdout]    |             help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/lib.rs:53:13
[INFO] [stdout]    |
[INFO] [stdout] 53 |         let mut pos: usize;
[INFO] [stdout]    |             ----^^^
[INFO] [stdout]    |             |
[INFO] [stdout]    |             help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variants `Root` and `Link` are never constructed
[INFO] [stdout]  --> src/lib.rs:7:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | enum SetItem<ValueType> {
[INFO] [stdout]   |      ------- variants in this enum
[INFO] [stdout] 7 |     Root(ValueType, u32),
[INFO] [stdout]   |     ^^^^
[INFO] [stdout] 8 |     Link(Box<SetItem<ValueType>>)
[INFO] [stdout]   |     ^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `SetItem` has a derived impl for the trait `Clone`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 5 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.09s
[INFO] running `Command { std: "docker" "inspect" "9e4b4e92372eaf306c552a2282dd30e83c4b0ddee3a589a4ee4825fe6adff2db", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9e4b4e92372eaf306c552a2282dd30e83c4b0ddee3a589a4ee4825fe6adff2db", kill_on_drop: false }`
[INFO] [stdout] 9e4b4e92372eaf306c552a2282dd30e83c4b0ddee3a589a4ee4825fe6adff2db
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc1/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" "RUSTDOCFLAGS=--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@sha256:5ff2268d62e97bff2cde7d5815dd6ed5b47097566f13b8d0ca110b04b60e07ed" "/opt/rustwide/cargo-home/bin/cargo" "+1.69.0" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] afdae818c57e664c09d955d07e131373de8abe2a2ffe6d91347204235892c250
[INFO] running `Command { std: "docker" "start" "-a" "afdae818c57e664c09d955d07e131373de8abe2a2ffe6d91347204235892c250", kill_on_drop: false }`
[INFO] [stdout] warning: unused import: `std::rc::Rc`
[INFO] [stdout]  --> src/lib.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use std::rc::Rc;
[INFO] [stdout]   |     ^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `p`
[INFO] [stdout]   --> src/lib.rs:37:18
[INFO] [stdout]    |
[INFO] [stdout] 37 |             Some(p) => return,
[INFO] [stdout]    |                  ^ help: if this is intentional, prefix it with an underscore: `_p`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/lib.rs:35:13
[INFO] [stdout]    |
[INFO] [stdout] 35 |         let mut len = &mut self.set_size;
[INFO] [stdout]    |             ----^^^
[INFO] [stdout]    |             |
[INFO] [stdout]    |             help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/lib.rs:53:13
[INFO] [stdout]    |
[INFO] [stdout] 53 |         let mut pos: usize;
[INFO] [stdout]    |             ----^^^
[INFO] [stdout]    |             |
[INFO] [stdout]    |             help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variants `Root` and `Link` are never constructed
[INFO] [stdout]  --> src/lib.rs:7:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | enum SetItem<ValueType> {
[INFO] [stdout]   |      ------- variants in this enum
[INFO] [stdout] 7 |     Root(ValueType, u32),
[INFO] [stdout]   |     ^^^^
[INFO] [stdout] 8 |     Link(Box<SetItem<ValueType>>)
[INFO] [stdout]   |     ^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `SetItem` has a derived impl for the trait `Clone`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 5 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]    Compiling disjoint-set v0.0.2 (/opt/rustwide/workdir)
[INFO] [stdout] warning: unused import: `std::rc::Rc`
[INFO] [stdout]  --> src/lib.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use std::rc::Rc;
[INFO] [stdout]   |     ^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `p`
[INFO] [stdout]   --> src/lib.rs:37:18
[INFO] [stdout]    |
[INFO] [stdout] 37 |             Some(p) => return,
[INFO] [stdout]    |                  ^ help: if this is intentional, prefix it with an underscore: `_p`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/lib.rs:35:13
[INFO] [stdout]    |
[INFO] [stdout] 35 |         let mut len = &mut self.set_size;
[INFO] [stdout]    |             ----^^^
[INFO] [stdout]    |             |
[INFO] [stdout]    |             help: remove this `mut`
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/lib.rs:53:13
[INFO] [stdout]    |
[INFO] [stdout] 53 |         let mut pos: usize;
[INFO] [stdout]    |             ----^^^
[INFO] [stdout]    |             |
[INFO] [stdout]    |             help: remove this `mut`
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variants `Root` and `Link` are never constructed
[INFO] [stdout]  --> src/lib.rs:7:5
[INFO] [stdout]   |
[INFO] [stdout] 6 | enum SetItem<ValueType> {
[INFO] [stdout]   |      ------- variants in this enum
[INFO] [stdout] 7 |     Root(ValueType, u32),
[INFO] [stdout]   |     ^^^^
[INFO] [stdout] 8 |     Link(Box<SetItem<ValueType>>)
[INFO] [stdout]   |     ^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `SetItem` has a derived impl for the trait `Clone`, but this is intentionally ignored during dead code analysis
[INFO] [stdout]   = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/lib.rs:106:5
[INFO] [stdout]     |
[INFO] [stdout] 106 |     ds.union(1, 2);
[INFO] [stdout]     |     ^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/lib.rs:107:5
[INFO] [stdout]     |
[INFO] [stdout] 107 |     ds.union(2, 3);
[INFO] [stdout]     |     ^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/lib.rs:118:5
[INFO] [stdout]     |
[INFO] [stdout] 118 |     ds.union(-1, 4);
[INFO] [stdout]     |     ^^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused `Result` that must be used
[INFO] [stdout]    --> src/lib.rs:119:5
[INFO] [stdout]     |
[INFO] [stdout] 119 |     ds.union(2, 4);
[INFO] [stdout]     |     ^^^^^^^^^^^^^^
[INFO] [stdout]     |
[INFO] [stdout]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 9 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.38s
[INFO] running `Command { std: "docker" "inspect" "afdae818c57e664c09d955d07e131373de8abe2a2ffe6d91347204235892c250", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "afdae818c57e664c09d955d07e131373de8abe2a2ffe6d91347204235892c250", kill_on_drop: false }`
[INFO] [stdout] afdae818c57e664c09d955d07e131373de8abe2a2ffe6d91347204235892c250
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5-tc1/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" "RUSTDOCFLAGS=--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@sha256:5ff2268d62e97bff2cde7d5815dd6ed5b47097566f13b8d0ca110b04b60e07ed" "/opt/rustwide/cargo-home/bin/cargo" "+1.69.0" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] f594b74dad2d2a468a4777d538fcfe26494baba17096914051aa1a40bbf9ff12
[INFO] running `Command { std: "docker" "start" "-a" "f594b74dad2d2a468a4777d538fcfe26494baba17096914051aa1a40bbf9ff12", kill_on_drop: false }`
[INFO] [stderr] warning: unused import: `std::rc::Rc`
[INFO] [stderr]  --> src/lib.rs:3:5
[INFO] [stderr]   |
[INFO] [stderr] 3 | use std::rc::Rc;
[INFO] [stderr]   |     ^^^^^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `p`
[INFO] [stderr]   --> src/lib.rs:37:18
[INFO] [stderr]    |
[INFO] [stderr] 37 |             Some(p) => return,
[INFO] [stderr]    |                  ^ help: if this is intentional, prefix it with an underscore: `_p`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_variables)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> src/lib.rs:35:13
[INFO] [stderr]    |
[INFO] [stderr] 35 |         let mut len = &mut self.set_size;
[INFO] [stderr]    |             ----^^^
[INFO] [stderr]    |             |
[INFO] [stderr]    |             help: remove this `mut`
[INFO] [stderr]    |
[INFO] [stderr]    = note: `#[warn(unused_mut)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> src/lib.rs:53:13
[INFO] [stderr]    |
[INFO] [stderr] 53 |         let mut pos: usize;
[INFO] [stderr]    |             ----^^^
[INFO] [stderr]    |             |
[INFO] [stderr]    |             help: remove this `mut`
[INFO] [stderr] 
[INFO] [stderr] warning: variants `Root` and `Link` are never constructed
[INFO] [stderr]  --> src/lib.rs:7:5
[INFO] [stderr]   |
[INFO] [stderr] 6 | enum SetItem<ValueType> {
[INFO] [stderr]   |      ------- variants in this enum
[INFO] [stderr] 7 |     Root(ValueType, u32),
[INFO] [stderr]   |     ^^^^
[INFO] [stderr] 8 |     Link(Box<SetItem<ValueType>>)
[INFO] [stderr]   |     ^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `SetItem` has a derived impl for the trait `Clone`, but this is intentionally ignored during dead code analysis
[INFO] [stderr]   = note: `#[warn(dead_code)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: `disjoint-set` (lib) generated 5 warnings (run `cargo fix --lib -p disjoint-set` to apply 4 suggestions)
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/lib.rs:106:5
[INFO] [stderr]     |
[INFO] [stderr] 106 |     ds.union(1, 2);
[INFO] [stderr]     |     ^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr]     = note: `#[warn(unused_must_use)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/lib.rs:107:5
[INFO] [stderr]     |
[INFO] [stderr] 107 |     ds.union(2, 3);
[INFO] [stderr]     |     ^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/lib.rs:118:5
[INFO] [stderr]     |
[INFO] [stderr] 118 |     ds.union(-1, 4);
[INFO] [stderr]     |     ^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr] 
[INFO] [stderr] warning: unused `Result` that must be used
[INFO] [stderr]    --> src/lib.rs:119:5
[INFO] [stderr]     |
[INFO] [stderr] 119 |     ds.union(2, 4);
[INFO] [stderr]     |     ^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: this `Result` may be an `Err` variant, which should be handled
[INFO] [stderr] 
[INFO] [stderr] warning: `disjoint-set` (lib test) generated 9 warnings (5 duplicates)
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.00s
[INFO] [stderr]      Running unittests src/lib.rs (/opt/rustwide/target/debug/deps/disjoint_set-81ab343fdb816cc2)
[INFO] [stdout] 
[INFO] [stdout] running 1 test
[INFO] [stdout] test it_works ... ok
[INFO] [stdout] 
[INFO] [stdout] test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stdout] 
[INFO] [stderr]    Doc-tests disjoint-set
[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" "f594b74dad2d2a468a4777d538fcfe26494baba17096914051aa1a40bbf9ff12", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "f594b74dad2d2a468a4777d538fcfe26494baba17096914051aa1a40bbf9ff12", kill_on_drop: false }`
[INFO] [stdout] f594b74dad2d2a468a4777d538fcfe26494baba17096914051aa1a40bbf9ff12
