[INFO] updating cached repository Ermain-12/Introduction-to-Rust
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/Ermain-12/Introduction-to-Rust
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/Ermain-12/Introduction-to-Rust" "work/ex/beta-1.38-1/sources/1.37.0/gh/Ermain-12/Introduction-to-Rust"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/Ermain-12/Introduction-to-Rust'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/Ermain-12/Introduction-to-Rust" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/Ermain-12/Introduction-to-Rust"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/Ermain-12/Introduction-to-Rust'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 19db755187092c11f3f3ea13092682fc7bc92786
[INFO] sha for GitHub repo Ermain-12/Introduction-to-Rust: 19db755187092c11f3f3ea13092682fc7bc92786
[INFO] validating manifest of Ermain-12/Introduction-to-Rust on toolchain 1.37.0
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of Ermain-12/Introduction-to-Rust on toolchain beta-2019-08-13
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing Ermain-12/Introduction-to-Rust
[INFO] finished frobbing Ermain-12/Introduction-to-Rust
[INFO] frobbed toml for Ermain-12/Introduction-to-Rust written to work/ex/beta-1.38-1/sources/1.37.0/gh/Ermain-12/Introduction-to-Rust/Cargo.toml
[INFO] started frobbing Ermain-12/Introduction-to-Rust
[INFO] finished frobbing Ermain-12/Introduction-to-Rust
[INFO] frobbed toml for Ermain-12/Introduction-to-Rust written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/Ermain-12/Introduction-to-Rust/Cargo.toml
[INFO] crate Ermain-12/Introduction-to-Rust already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing Ermain-12/Introduction-to-Rust against beta-2019-08-13 for beta-1.38-1
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.38-1/worker-0/beta-2019-08-13:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/Ermain-12/Introduction-to-Rust:/opt/crater/workdir:ro,Z" "-v" "/mnt/big/crater/work/local/cargo-home:/opt/crater/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/local/rustup-home:/opt/crater/rustup-home:ro,Z" "-e" "USER_ID=1000" "-e" "SOURCE_DIR=/opt/crater/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/crater/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/crater/cargo-home" "-e" "RUSTUP_HOME=/opt/crater/rustup-home" "-w" "/opt/crater/workdir" "-m" "1536M" "--network" "none" "rustops/crates-build-env" "/opt/crater/cargo-home/bin/cargo" "+beta-2019-08-13" "build" "--frozen"`
[INFO] [stdout] 530d4aebb26ceaa99d5fb8334920cd1fb01505f23110042dbf7900b494d45fdb
[INFO] running `"docker" "start" "-a" "530d4aebb26ceaa99d5fb8334920cd1fb01505f23110042dbf7900b494d45fdb"`
[INFO] [stderr]    Compiling regex v1.0.0
[INFO] [stderr]    Compiling memchr v2.0.1
[INFO] [stderr]    Compiling time v0.1.40
[INFO] [stderr]    Compiling regex-syntax v0.6.0
[INFO] [stderr]    Compiling thread_local v0.3.5
[INFO] [stderr]    Compiling aho-corasick v0.6.4
[INFO] [stderr]    Compiling hello_world v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> src/main.rs:27:8
[INFO] [stderr]    |
[INFO] [stderr] 27 |    let mut twenty_one = my_vec.pop();
[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]     Finished dev [unoptimized + debuginfo] target(s) in 21.88s
[INFO] running `"docker" "inspect" "530d4aebb26ceaa99d5fb8334920cd1fb01505f23110042dbf7900b494d45fdb"`
[INFO] running `"docker" "rm" "-f" "530d4aebb26ceaa99d5fb8334920cd1fb01505f23110042dbf7900b494d45fdb"`
[INFO] [stdout] 530d4aebb26ceaa99d5fb8334920cd1fb01505f23110042dbf7900b494d45fdb
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.38-1/worker-0/beta-2019-08-13:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/Ermain-12/Introduction-to-Rust:/opt/crater/workdir:ro,Z" "-v" "/mnt/big/crater/work/local/cargo-home:/opt/crater/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/local/rustup-home:/opt/crater/rustup-home:ro,Z" "-e" "USER_ID=1000" "-e" "SOURCE_DIR=/opt/crater/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/crater/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/crater/cargo-home" "-e" "RUSTUP_HOME=/opt/crater/rustup-home" "-w" "/opt/crater/workdir" "-m" "1536M" "--network" "none" "rustops/crates-build-env" "/opt/crater/cargo-home/bin/cargo" "+beta-2019-08-13" "test" "--frozen" "--no-run"`
[INFO] [stdout] c36eb491c20ce5bffed65d5e4b9b34855eb5eea40dd2cea89a8e693c455ca0ce
[INFO] running `"docker" "start" "-a" "c36eb491c20ce5bffed65d5e4b9b34855eb5eea40dd2cea89a8e693c455ca0ce"`
[INFO] [stderr]    Compiling hello_world v0.1.0 (/opt/crater/workdir)
[INFO] [stderr] warning: variable does not need to be mutable
[INFO] [stderr]   --> src/main.rs:27:8
[INFO] [stderr]    |
[INFO] [stderr] 27 |    let mut twenty_one = my_vec.pop();
[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]     Finished dev [unoptimized + debuginfo] target(s) in 0.71s
[INFO] running `"docker" "inspect" "c36eb491c20ce5bffed65d5e4b9b34855eb5eea40dd2cea89a8e693c455ca0ce"`
[INFO] running `"docker" "rm" "-f" "c36eb491c20ce5bffed65d5e4b9b34855eb5eea40dd2cea89a8e693c455ca0ce"`
[INFO] [stdout] c36eb491c20ce5bffed65d5e4b9b34855eb5eea40dd2cea89a8e693c455ca0ce
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.38-1/worker-0/beta-2019-08-13:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/Ermain-12/Introduction-to-Rust:/opt/crater/workdir:ro,Z" "-v" "/mnt/big/crater/work/local/cargo-home:/opt/crater/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/local/rustup-home:/opt/crater/rustup-home:ro,Z" "-e" "USER_ID=1000" "-e" "SOURCE_DIR=/opt/crater/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/crater/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/crater/cargo-home" "-e" "RUSTUP_HOME=/opt/crater/rustup-home" "-w" "/opt/crater/workdir" "-m" "1536M" "--network" "none" "rustops/crates-build-env" "/opt/crater/cargo-home/bin/cargo" "+beta-2019-08-13" "test" "--frozen"`
[INFO] [stdout] 75c9a389960bc859e3d0eaaa53ce9c7197153dc0690bb6c2928b97568e50e006
[INFO] running `"docker" "start" "-a" "75c9a389960bc859e3d0eaaa53ce9c7197153dc0690bb6c2928b97568e50e006"`
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 0.05s
[INFO] [stderr]      Running /opt/crater/target/debug/deps/hello_world-c7915b159ac8ecc8
[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
[INFO] [stdout] 
[INFO] running `"docker" "inspect" "75c9a389960bc859e3d0eaaa53ce9c7197153dc0690bb6c2928b97568e50e006"`
[INFO] running `"docker" "rm" "-f" "75c9a389960bc859e3d0eaaa53ce9c7197153dc0690bb6c2928b97568e50e006"`
[INFO] [stdout] 75c9a389960bc859e3d0eaaa53ce9c7197153dc0690bb6c2928b97568e50e006