[INFO] cloning repository https://github.com/mister36/proof-of-work
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/mister36/proof-of-work" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmister36%2Fproof-of-work", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmister36%2Fproof-of-work'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] a42df606b92570bef08c364a1dd6e105de0b6602
[INFO] testing mister36/proof-of-work against 1.59.0 for beta-1.60-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmister36%2Fproof-of-work" "/workspace/builds/worker-19/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-19/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/mister36/proof-of-work on toolchain 1.59.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.59.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/mister36/proof-of-work
[INFO] finished tweaking git repo https://github.com/mister36/proof-of-work
[INFO] tweaked toml for git repo https://github.com/mister36/proof-of-work written to /workspace/builds/worker-19/source/Cargo.toml
[INFO] crate git repo https://github.com/mister36/proof-of-work already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.59.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-19/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-19/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@sha256:0cd99ca24d8e8c98e67c542213511d985b8778b5bdcbb160e038429496686047" "/opt/rustwide/cargo-home/bin/cargo" "+1.59.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 77373b3255f9f8cc53c32fe67a2d6b4bd2505ccf7fea1263e1591fa73e64a3bd
[INFO] running `Command { std: "docker" "start" "-a" "77373b3255f9f8cc53c32fe67a2d6b4bd2505ccf7fea1263e1591fa73e64a3bd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "77373b3255f9f8cc53c32fe67a2d6b4bd2505ccf7fea1263e1591fa73e64a3bd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "77373b3255f9f8cc53c32fe67a2d6b4bd2505ccf7fea1263e1591fa73e64a3bd", kill_on_drop: false }`
[INFO] [stdout] 77373b3255f9f8cc53c32fe67a2d6b4bd2505ccf7fea1263e1591fa73e64a3bd
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-19/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-19/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" "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@sha256:0cd99ca24d8e8c98e67c542213511d985b8778b5bdcbb160e038429496686047" "/opt/rustwide/cargo-home/bin/cargo" "+1.59.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 9b4cef6c060da6ad5e95f278742a788e9a813ea5dd24201d8418a25f00a775e0
[INFO] running `Command { std: "docker" "start" "-a" "9b4cef6c060da6ad5e95f278742a788e9a813ea5dd24201d8418a25f00a775e0", kill_on_drop: false }`
[INFO] [stderr]    Compiling cpufeatures v0.1.5
[INFO] [stderr]    Compiling hex-literal v0.3.3
[INFO] [stderr]    Compiling byteorder v1.4.3
[INFO] [stderr]    Compiling generic-array v0.14.4
[INFO] [stderr]    Compiling digest v0.9.0
[INFO] [stderr]    Compiling block-buffer v0.9.0
[INFO] [stderr]    Compiling sha2 v0.9.5
[INFO] [stderr]    Compiling proof-of-work v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: field is never read: `contents`
[INFO] [stdout]   --> src/chain/lib.rs:17:5
[INFO] [stdout]    |
[INFO] [stdout] 17 |     contents: String,
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `prev_hash`
[INFO] [stdout]   --> src/chain/lib.rs:23:5
[INFO] [stdout]    |
[INFO] [stdout] 23 |     prev_hash: Vec<u8>,
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `timestamp`
[INFO] [stdout]   --> src/chain/lib.rs:29:5
[INFO] [stdout]    |
[INFO] [stdout] 29 |     timestamp: SystemTime
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::io::Cursor`
[INFO] [stdout]  --> src/main.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::io::Cursor;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `Sha256`
[INFO] [stdout]  --> src/main.rs:2:12
[INFO] [stdout]   |
[INFO] [stdout] 2 | use sha2::{Sha256, Digest};
[INFO] [stdout]   |            ^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `hex_literal::hex`
[INFO] [stdout]  --> src/main.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use hex_literal::hex;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused imports: `BigEndian`, `ReadBytesExt`
[INFO] [stdout]  --> src/main.rs:4:17
[INFO] [stdout]   |
[INFO] [stdout] 4 | use byteorder::{BigEndian, ReadBytesExt};
[INFO] [stdout]   |                 ^^^^^^^^^  ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `Digest`
[INFO] [stdout]  --> src/main.rs:2:20
[INFO] [stdout]   |
[INFO] [stdout] 2 | use sha2::{Sha256, Digest};
[INFO] [stdout]   |                    ^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `block_2`
[INFO] [stdout]   --> src/main.rs:11:9
[INFO] [stdout]    |
[INFO] [stdout] 11 |     let block_2 = Block::new(Some(&chain.blocks[0]), "Next awesome string".to_string());
[INFO] [stdout]    |         ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_block_2`
[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/main.rs:8:9
[INFO] [stdout]   |
[INFO] [stdout] 8 |     let mut chain = Blockchain {blocks: vec![block_1]};
[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] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 3.64s
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] running `Command { std: "docker" "inspect" "9b4cef6c060da6ad5e95f278742a788e9a813ea5dd24201d8418a25f00a775e0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "9b4cef6c060da6ad5e95f278742a788e9a813ea5dd24201d8418a25f00a775e0", kill_on_drop: false }`
[INFO] [stdout] 9b4cef6c060da6ad5e95f278742a788e9a813ea5dd24201d8418a25f00a775e0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-19/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-19/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" "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@sha256:0cd99ca24d8e8c98e67c542213511d985b8778b5bdcbb160e038429496686047" "/opt/rustwide/cargo-home/bin/cargo" "+1.59.0" "test" "--frozen" "--no-run" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] d2db7d5593224c99ea7df5c85def0819d20c3627332dd9172972069998a5e26f
[INFO] running `Command { std: "docker" "start" "-a" "d2db7d5593224c99ea7df5c85def0819d20c3627332dd9172972069998a5e26f", kill_on_drop: false }`
[INFO] [stderr]    Compiling proof-of-work v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] warning: field is never read: `contents`
[INFO] [stdout]   --> src/chain/lib.rs:17:5
[INFO] [stdout]    |
[INFO] [stdout] 17 |     contents: String,
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `prev_hash`
[INFO] [stdout]   --> src/chain/lib.rs:23:5
[INFO] [stdout]    |
[INFO] [stdout] 23 |     prev_hash: Vec<u8>,
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `timestamp`
[INFO] [stdout]   --> src/chain/lib.rs:29:5
[INFO] [stdout]    |
[INFO] [stdout] 29 |     timestamp: SystemTime
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `std::io::Cursor`
[INFO] [stdout]  --> src/main.rs:1:5
[INFO] [stdout]   |
[INFO] [stdout] 1 | use std::io::Cursor;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^
[INFO] [stdout]   |
[INFO] [stdout]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `Sha256`
[INFO] [stdout]  --> src/main.rs:2:12
[INFO] [stdout]   |
[INFO] [stdout] 2 | use sha2::{Sha256, Digest};
[INFO] [stdout]   |            ^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `hex_literal::hex`
[INFO] [stdout]  --> src/main.rs:3:5
[INFO] [stdout]   |
[INFO] [stdout] 3 | use hex_literal::hex;
[INFO] [stdout]   |     ^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused imports: `BigEndian`, `ReadBytesExt`
[INFO] [stdout]  --> src/main.rs:4:17
[INFO] [stdout]   |
[INFO] [stdout] 4 | use byteorder::{BigEndian, ReadBytesExt};
[INFO] [stdout]   |                 ^^^^^^^^^  ^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused import: `Digest`
[INFO] [stdout]  --> src/main.rs:2:20
[INFO] [stdout]   |
[INFO] [stdout] 2 | use sha2::{Sha256, Digest};
[INFO] [stdout]   |                    ^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: unused variable: `block_2`
[INFO] [stdout]   --> src/main.rs:11:9
[INFO] [stdout]    |
[INFO] [stdout] 11 |     let block_2 = Block::new(Some(&chain.blocks[0]), "Next awesome string".to_string());
[INFO] [stdout]    |         ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_block_2`
[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/main.rs:8:9
[INFO] [stdout]   |
[INFO] [stdout] 8 |     let mut chain = Blockchain {blocks: vec![block_1]};
[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: field is never read: `contents`
[INFO] [stdout]   --> src/chain/lib.rs:17:5
[INFO] [stdout]    |
[INFO] [stdout] 17 |     contents: String,
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `prev_hash`
[INFO] [stdout]   --> src/chain/lib.rs:23:5
[INFO] [stdout]    |
[INFO] [stdout] 23 |     prev_hash: Vec<u8>,
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: field is never read: `timestamp`
[INFO] [stdout]   --> src/chain/lib.rs:29:5
[INFO] [stdout]    |
[INFO] [stdout] 29 |     timestamp: SystemTime
[INFO] [stdout]    |     ^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 7 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 3 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.44s
[INFO] running `Command { std: "docker" "inspect" "d2db7d5593224c99ea7df5c85def0819d20c3627332dd9172972069998a5e26f", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "d2db7d5593224c99ea7df5c85def0819d20c3627332dd9172972069998a5e26f", kill_on_drop: false }`
[INFO] [stdout] d2db7d5593224c99ea7df5c85def0819d20c3627332dd9172972069998a5e26f
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-19/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-19/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" "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@sha256:0cd99ca24d8e8c98e67c542213511d985b8778b5bdcbb160e038429496686047" "/opt/rustwide/cargo-home/bin/cargo" "+1.59.0" "test" "--frozen", kill_on_drop: false }`
[INFO] [stdout] 767f61ca6bb78c4e41e118bd2c6fe30c105d442799d033db00ba338ee85515f4
[INFO] running `Command { std: "docker" "start" "-a" "767f61ca6bb78c4e41e118bd2c6fe30c105d442799d033db00ba338ee85515f4", kill_on_drop: false }`
[INFO] [stdout] 
[INFO] [stderr] warning: field is never read: `contents`
[INFO] [stdout] running 0 tests
[INFO] [stderr]   --> src/chain/lib.rs:17:5
[INFO] [stdout] 
[INFO] [stderr]    |
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stderr] 17 |     contents: String,
[INFO] [stdout] 
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stderr]    |
[INFO] [stdout] running 0 tests
[INFO] [stderr]    = note: `#[warn(dead_code)]` on by default
[INFO] [stdout] 
[INFO] [stderr] 
[INFO] [stdout] test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
[INFO] [stderr] warning: field is never read: `prev_hash`
[INFO] [stdout] 
[INFO] [stderr]   --> src/chain/lib.rs:23:5
[INFO] [stderr]    |
[INFO] [stderr] 23 |     prev_hash: Vec<u8>,
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: field is never read: `timestamp`
[INFO] [stderr]   --> src/chain/lib.rs:29:5
[INFO] [stderr]    |
[INFO] [stderr] 29 |     timestamp: SystemTime
[INFO] [stderr]    |     ^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: `proof-of-work` (lib) generated 3 warnings
[INFO] [stderr] warning: `proof-of-work` (lib test) generated 3 warnings (3 duplicates)
[INFO] [stderr] warning: unused import: `std::io::Cursor`
[INFO] [stderr]  --> src/main.rs:1:5
[INFO] [stderr]   |
[INFO] [stderr] 1 | use std::io::Cursor;
[INFO] [stderr]   |     ^^^^^^^^^^^^^^^
[INFO] [stderr]   |
[INFO] [stderr]   = note: `#[warn(unused_imports)]` on by default
[INFO] [stderr] 
[INFO] [stderr] warning: unused import: `Sha256`
[INFO] [stderr]  --> src/main.rs:2:12
[INFO] [stderr]   |
[INFO] [stderr] 2 | use sha2::{Sha256, Digest};
[INFO] [stderr]   |            ^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: unused import: `hex_literal::hex`
[INFO] [stderr]  --> src/main.rs:3:5
[INFO] [stderr]   |
[INFO] [stderr] 3 | use hex_literal::hex;
[INFO] [stderr]   |     ^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: unused imports: `BigEndian`, `ReadBytesExt`
[INFO] [stderr]  --> src/main.rs:4:17
[INFO] [stderr]   |
[INFO] [stderr] 4 | use byteorder::{BigEndian, ReadBytesExt};
[INFO] [stderr]   |                 ^^^^^^^^^  ^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: unused import: `Digest`
[INFO] [stderr]  --> src/main.rs:2:20
[INFO] [stderr]   |
[INFO] [stderr] 2 | use sha2::{Sha256, Digest};
[INFO] [stderr]   |                    ^^^^^^
[INFO] [stderr] 
[INFO] [stderr] warning: unused variable: `block_2`
[INFO] [stderr]   --> src/main.rs:11:9
[INFO] [stderr]    |
[INFO] [stderr] 11 |     let block_2 = Block::new(Some(&chain.blocks[0]), "Next awesome string".to_string());
[INFO] [stderr]    |         ^^^^^^^ help: if this is intentional, prefix it with an underscore: `_block_2`
[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/main.rs:8:9
[INFO] [stderr]   |
[INFO] [stderr] 8 |     let mut chain = Blockchain {blocks: vec![block_1]};
[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: `proof-of-work` (bin "bin" test) generated 7 warnings
[INFO] [stderr]     Finished test [unoptimized + debuginfo] target(s) in 0.01s
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/chain-1252a311608454ba)
[INFO] [stderr]      Running unittests (/opt/rustwide/target/debug/deps/bin-80ef2dac256bee5a)
[INFO] [stderr]    Doc-tests chain
[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" "767f61ca6bb78c4e41e118bd2c6fe30c105d442799d033db00ba338ee85515f4", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "767f61ca6bb78c4e41e118bd2c6fe30c105d442799d033db00ba338ee85515f4", kill_on_drop: false }`
[INFO] [stdout] 767f61ca6bb78c4e41e118bd2c6fe30c105d442799d033db00ba338ee85515f4