[INFO] fetching crate tac 0.2.3...
[INFO] checking tac-0.2.3 against try#9b49d8c6c904f63eb486fe51b14bbe0aa2feda4c for pr-79472
[INFO] extracting crate tac 0.2.3 into /workspace/builds/worker-1/source
[INFO] validating manifest of crates.io crate tac 0.2.3 on toolchain 9b49d8c6c904f63eb486fe51b14bbe0aa2feda4c
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+9b49d8c6c904f63eb486fe51b14bbe0aa2feda4c" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking crates.io crate tac 0.2.3
[INFO] finished tweaking crates.io crate tac 0.2.3
[INFO] tweaked toml for crates.io crate tac 0.2.3 written to /workspace/builds/worker-1/source/Cargo.toml
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+9b49d8c6c904f63eb486fe51b14bbe0aa2feda4c" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+9b49d8c6c904f63eb486fe51b14bbe0aa2feda4c" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded fuchsia-cprng v0.1.1
[INFO] [stderr]   Downloaded libc v0.2.81
[INFO] [stderr]   Downloaded memmap v0.5.2
[INFO] [stderr]   Downloaded rand v0.4.6
[INFO] [stderr]   Downloaded winapi-x86_64-pc-windows-gnu v0.4.0
[INFO] [stderr]   Downloaded winapi-build v0.1.1
[INFO] [stderr]   Downloaded rand_core v0.3.1
[INFO] [stderr]   Downloaded winapi v0.3.9
[INFO] [stderr]   Downloaded rand v0.3.23
[INFO] [stderr]   Downloaded fs2 v0.4.3
[INFO] [stderr]   Downloaded kernel32-sys v0.2.2
[INFO] [stderr]   Downloaded rand_core v0.4.2
[INFO] [stderr]   Downloaded uuid v0.4.0
[INFO] [stderr]   Downloaded rdrand v0.4.0
[INFO] [stderr]   Downloaded winapi-i686-pc-windows-gnu v0.4.0
[INFO] [stderr]   Downloaded winapi v0.2.8
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+9b49d8c6c904f63eb486fe51b14bbe0aa2feda4c" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 490e4b716ae871bbee91099c51f7b58613fe4af6de7e407f21163fc8fd2e1ec0
[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" "490e4b716ae871bbee91099c51f7b58613fe4af6de7e407f21163fc8fd2e1ec0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "490e4b716ae871bbee91099c51f7b58613fe4af6de7e407f21163fc8fd2e1ec0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "490e4b716ae871bbee91099c51f7b58613fe4af6de7e407f21163fc8fd2e1ec0", kill_on_drop: false }`
[INFO] [stdout] 490e4b716ae871bbee91099c51f7b58613fe4af6de7e407f21163fc8fd2e1ec0
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1/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:c8ac004eab7d63a0ad09a2dde3d3353ba464f767bee4de425dc8f74c46a1905e" "/opt/rustwide/cargo-home/bin/cargo" "+9b49d8c6c904f63eb486fe51b14bbe0aa2feda4c" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 5ffdc67fcf61efda4adc7753dda4eb94e61b1ca1ecf9fed8d1e78b3d5240761c
[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" "5ffdc67fcf61efda4adc7753dda4eb94e61b1ca1ecf9fed8d1e78b3d5240761c", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]     Checking memmap v0.5.2
[INFO] [stderr]     Checking rand v0.3.23
[INFO] [stderr]     Checking uuid v0.4.0
[INFO] [stderr]     Checking tac v0.2.3 (/opt/rustwide/workdir)
[INFO] [stdout] warning: the item `Write` is imported redundantly
[INFO] [stdout]   --> src/main.rs:72:9
[INFO] [stdout]    |
[INFO] [stdout] 5  | use std::io::{StdoutLock, Write};
[INFO] [stdout]    |                           ----- the item `Write` is already imported here
[INFO] [stdout] ...
[INFO] [stdout] 72 |     use std::io::Write;
[INFO] [stdout]    |         ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: the item `Write` is imported redundantly
[INFO] [stdout]   --> src/main.rs:72:9
[INFO] [stdout]    |
[INFO] [stdout] 5  | use std::io::{StdoutLock, Write};
[INFO] [stdout]    |                           ----- the item `Write` is already imported here
[INFO] [stdout] ...
[INFO] [stdout] 72 |     use std::io::Write;
[INFO] [stdout]    |         ^^^^^^^^^^^^^^
[INFO] [stdout]    |
[INFO] [stdout]    = note: `#[warn(unused_imports)]` on by default
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/main.rs:64:16
[INFO] [stdout]    |
[INFO] [stdout] 64 | fn print_bytes(mut stdout: &mut StdoutLock, bytes: &[u8]) {
[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/main.rs:64:16
[INFO] [stdout]    |
[INFO] [stdout] 64 | fn print_bytes(mut stdout: &mut StdoutLock, bytes: &[u8]) {
[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: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: 2 warnings emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 1.57s
[INFO] running `Command { std: "docker" "inspect" "5ffdc67fcf61efda4adc7753dda4eb94e61b1ca1ecf9fed8d1e78b3d5240761c", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "5ffdc67fcf61efda4adc7753dda4eb94e61b1ca1ecf9fed8d1e78b3d5240761c", kill_on_drop: false }`
[INFO] [stdout] 5ffdc67fcf61efda4adc7753dda4eb94e61b1ca1ecf9fed8d1e78b3d5240761c