[INFO] fetching crate lmarkov 0.1.0...
[INFO] checking lmarkov-0.1.0 against master#cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c for pr-143170
[INFO] extracting crate lmarkov 0.1.0 into /workspace/builds/worker-5-tc1/source
[INFO] started tweaking crates.io crate lmarkov 0.1.0
[INFO] finished tweaking crates.io crate lmarkov 0.1.0
[INFO] tweaked toml for crates.io crate lmarkov 0.1.0 written to /workspace/builds/worker-5-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate lmarkov 0.1.0 on toolchain cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c" "generate-lockfile" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]      Locking 21 packages to latest compatible versions
[INFO] [stderr]       Adding rand v0.7.3 (available: v0.9.1)
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c" "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@sha256:90999bfc7ae267e83380e433d8e61a7c072ca6729e92edbae886d3423b3a6f4c" "/opt/rustwide/cargo-home/bin/cargo" "+cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 2e41ca4ff5be52b4bb101538841f7e0ac3ae2fb79c7391c3bf18b7457a649c72
[INFO] running `Command { std: "docker" "start" "-a" "2e41ca4ff5be52b4bb101538841f7e0ac3ae2fb79c7391c3bf18b7457a649c72", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "2e41ca4ff5be52b4bb101538841f7e0ac3ae2fb79c7391c3bf18b7457a649c72", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "2e41ca4ff5be52b4bb101538841f7e0ac3ae2fb79c7391c3bf18b7457a649c72", kill_on_drop: false }`
[INFO] [stdout] 2e41ca4ff5be52b4bb101538841f7e0ac3ae2fb79c7391c3bf18b7457a649c72
[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=forbid" "-e" "RUSTDOCFLAGS=--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" "ghcr.io/rust-lang/crates-build-env/linux@sha256:90999bfc7ae267e83380e433d8e61a7c072ca6729e92edbae886d3423b3a6f4c" "/opt/rustwide/cargo-home/bin/cargo" "+cf38b8e663f15db10ce49d7bbce02c99fc3dbc0c" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 8e353e3187308215f6c0cbb09f426e5a99eea2d37c209bb28ffcf3ee881fbef3
[INFO] running `Command { std: "docker" "start" "-a" "8e353e3187308215f6c0cbb09f426e5a99eea2d37c209bb28ffcf3ee881fbef3", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.174
[INFO] [stderr]    Compiling zerocopy v0.8.26
[INFO] [stderr]     Checking getrandom v0.1.16
[INFO] [stderr]     Checking rand_core v0.5.1
[INFO] [stderr]     Checking ppv-lite86 v0.2.21
[INFO] [stderr]     Checking rand_chacha v0.2.2
[INFO] [stderr]     Checking rand v0.7.3
[INFO] [stderr]     Checking lmarkov v0.1.0 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0277]: `Option<String>` doesn't implement `std::fmt::Display`
[INFO] [stdout]   --> src/tests.rs:10:20
[INFO] [stdout]    |
[INFO] [stdout] 10 |     println!("{}", chain.generate());
[INFO] [stdout]    |               --   ^^^^^^^^^^^^^^^^ `Option<String>` cannot be formatted with the default formatter
[INFO] [stdout]    |               |
[INFO] [stdout]    |               required by this formatting parameter
[INFO] [stdout]    |
[INFO] [stdout]    = help: the trait `std::fmt::Display` is not implemented for `Option<String>`
[INFO] [stdout]    = note: in format strings you may be able to use `{:?}` (or {:#?} for pretty-print) instead
[INFO] [stdout]    = note: this error originates in the macro `$crate::format_args_nl` which comes from the expansion of the macro `println` (in Nightly builds, run with -Z macro-backtrace for more info)
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0277`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `lmarkov` (lib test) due to 1 previous error
[INFO] running `Command { std: "docker" "inspect" "8e353e3187308215f6c0cbb09f426e5a99eea2d37c209bb28ffcf3ee881fbef3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8e353e3187308215f6c0cbb09f426e5a99eea2d37c209bb28ffcf3ee881fbef3", kill_on_drop: false }`
[INFO] [stdout] 8e353e3187308215f6c0cbb09f426e5a99eea2d37c209bb28ffcf3ee881fbef3