[INFO] updating cached repository https://github.com/rmsthebest/nullable-first-follow
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "-c" "remote.origin.fetch=refs/heads/*:refs/heads/*" "fetch" "origin" "--force" "--prune", kill_on_drop: false }`
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] fac3a77c4de1f7e645a1fbdf8369b31179f69de5
[INFO] checking rmsthebest/nullable-first-follow against master#c724b67e1b474262917a5154d74e7072267593fe for pr-74315
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Frmsthebest%2Fnullable-first-follow" "/workspace/builds/worker-14/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-14/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/rmsthebest/nullable-first-follow on toolchain c724b67e1b474262917a5154d74e7072267593fe
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+c724b67e1b474262917a5154d74e7072267593fe" "read-manifest" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/rmsthebest/nullable-first-follow
[INFO] finished tweaking git repo https://github.com/rmsthebest/nullable-first-follow
[INFO] tweaked toml for git repo https://github.com/rmsthebest/nullable-first-follow written to /workspace/builds/worker-14/source/Cargo.toml
[INFO] crate git repo https://github.com/rmsthebest/nullable-first-follow already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+c724b67e1b474262917a5154d74e7072267593fe" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr] error: the lock file /workspace/builds/worker-14/source/Cargo.lock needs to be updated but --locked was passed to prevent this
[INFO] [stderr] If you want to try to generate the lock file without accessing the network, use the --offline flag.
[INFO] the lockfile is outdated, regenerating it
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+c724b67e1b474262917a5154d74e7072267593fe" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update", kill_on_drop: false }`
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+c724b67e1b474262917a5154d74e7072267593fe" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:d9fbb4e2287ab3795bdefaf705efb7541a8875c13bce71e067d6b01dc5ed759b" "/opt/rustwide/cargo-home/bin/cargo" "+c724b67e1b474262917a5154d74e7072267593fe" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] e5bc6dff75edbc2c89a22d2edb272510e51d035b6a473fa3c08cd64f06c4af58
[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" "e5bc6dff75edbc2c89a22d2edb272510e51d035b6a473fa3c08cd64f06c4af58", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "e5bc6dff75edbc2c89a22d2edb272510e51d035b6a473fa3c08cd64f06c4af58", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "e5bc6dff75edbc2c89a22d2edb272510e51d035b6a473fa3c08cd64f06c4af58", kill_on_drop: false }`
[INFO] [stdout] e5bc6dff75edbc2c89a22d2edb272510e51d035b6a473fa3c08cd64f06c4af58
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-14/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" "MAP_USER_ID=0" "-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" "--network" "none" "rustops/crates-build-env@sha256:d9fbb4e2287ab3795bdefaf705efb7541a8875c13bce71e067d6b01dc5ed759b" "/opt/rustwide/cargo-home/bin/cargo" "+c724b67e1b474262917a5154d74e7072267593fe" "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] bcf816184aa0446f2fe6d087fe8c0fda00306ed004034590322116c6cdda06bf
[INFO] running `Command { std: "docker" "start" "-a" "bcf816184aa0446f2fe6d087fe8c0fda00306ed004034590322116c6cdda06bf", kill_on_drop: false }`
[INFO] [stderr]    Compiling byteorder v1.3.4
[INFO] [stderr]     Checking scopeguard v0.3.3
[INFO] [stderr]     Checking hashbrown v0.1.8
[INFO] [stderr]     Checking nff v0.1.2 (/opt/rustwide/workdir)
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/lib.rs:61:17
[INFO] [stdout]    |
[INFO] [stdout] 61 |             let mut rhs = side.next().expect("Missing right hand side").trim().chars();
[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: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] warning: variable does not need to be mutable
[INFO] [stdout]   --> src/lib.rs:61:17
[INFO] [stdout]    |
[INFO] [stdout] 61 |             let mut rhs = side.next().expect("Missing right hand side").trim().chars();
[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: 1 warning emitted
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stderr]     Finished dev [unoptimized + debuginfo] target(s) in 4.12s
[INFO] running `Command { std: "docker" "inspect" "bcf816184aa0446f2fe6d087fe8c0fda00306ed004034590322116c6cdda06bf", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "bcf816184aa0446f2fe6d087fe8c0fda00306ed004034590322116c6cdda06bf", kill_on_drop: false }`
[INFO] [stdout] bcf816184aa0446f2fe6d087fe8c0fda00306ed004034590322116c6cdda06bf