[INFO] cloning repository https://github.com/hyhugh/rustlings_answers
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/hyhugh/rustlings_answers" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fhyhugh%2Frustlings_answers", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fhyhugh%2Frustlings_answers'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] d76e9af3a8f9a471100f845bdaab8a8ea2a98728
[INFO] checking hyhugh/rustlings_answers against master#385fa9d845dd326c6bbfd58c22244215e431948a for never-type-fallback-to-never
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fhyhugh%2Frustlings_answers" "/workspace/builds/worker-7-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-7-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/hyhugh/rustlings_answers on toolchain 385fa9d845dd326c6bbfd58c22244215e431948a
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+385fa9d845dd326c6bbfd58c22244215e431948a" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/hyhugh/rustlings_answers
[INFO] finished tweaking git repo https://github.com/hyhugh/rustlings_answers
[INFO] tweaked toml for git repo https://github.com/hyhugh/rustlings_answers written to /workspace/builds/worker-7-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/hyhugh/rustlings_answers already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+385fa9d845dd326c6bbfd58c22244215e431948a" "fetch" "--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] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+385fa9d845dd326c6bbfd58c22244215e431948a" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 515c913fd1f01d941500c31dda7b38b9121ea6e4288fdca77275b664234e70d3
[INFO] running `Command { std: "docker" "start" "-a" "515c913fd1f01d941500c31dda7b38b9121ea6e4288fdca77275b664234e70d3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "515c913fd1f01d941500c31dda7b38b9121ea6e4288fdca77275b664234e70d3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "515c913fd1f01d941500c31dda7b38b9121ea6e4288fdca77275b664234e70d3", kill_on_drop: false }`
[INFO] [stdout] 515c913fd1f01d941500c31dda7b38b9121ea6e4288fdca77275b664234e70d3
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+385fa9d845dd326c6bbfd58c22244215e431948a" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 25c21f9e58e95e054f6b74d62c4a49c5ccdf1d6a0635cf3c3bbee7cc6070252b
[INFO] running `Command { std: "docker" "start" "-a" "25c21f9e58e95e054f6b74d62c4a49c5ccdf1d6a0635cf3c3bbee7cc6070252b", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.93
[INFO] [stderr]    Compiling proc-macro2 v1.0.26
[INFO] [stderr]    Compiling syn v1.0.70
[INFO] [stderr]    Compiling serde_derive v1.0.125
[INFO] [stderr]     Checking regex-syntax v0.6.23
[INFO] [stderr]    Compiling serde v1.0.125
[INFO] [stderr]     Checking smallvec v1.6.1
[INFO] [stderr]    Compiling ryu v1.0.5
[INFO] [stderr]    Compiling num-traits v0.2.14
[INFO] [stderr]     Checking instant v0.1.9
[INFO] [stderr]     Checking lock_api v0.4.3
[INFO] [stderr]    Compiling unicode-segmentation v1.7.1
[INFO] [stderr]     Checking slab v0.4.3
[INFO] [stderr]    Compiling serde_json v1.0.64
[INFO] [stderr]    Compiling argh_shared v0.1.4
[INFO] [stderr]     Checking same-file v1.0.6
[INFO] [stderr]     Checking predicates-core v1.0.2
[INFO] [stderr]     Checking itoa v0.4.7
[INFO] [stderr]     Checking lazycell v1.3.0
[INFO] [stderr]    Compiling escargot v0.4.0
[INFO] [stderr]     Checking walkdir v2.3.2
[INFO] [stderr]     Checking predicates-tree v1.0.2
[INFO] [stderr]     Checking glob v0.3.0
[INFO] [stderr]    Compiling heck v0.3.2
[INFO] [stderr]     Checking parking_lot_core v0.8.3
[INFO] [stderr]     Checking iovec v0.1.4
[INFO] [stderr]     Checking net2 v0.2.37
[INFO] [stderr]     Checking terminal_size v0.1.16
[INFO] [stderr]     Checking inotify-sys v0.1.5
[INFO] [stderr]     Checking atty v0.2.14
[INFO] [stderr]     Checking termios v0.3.3
[INFO] [stderr]     Checking clicolors-control v1.0.1
[INFO] [stderr]     Checking filetime v0.2.14
[INFO] [stderr]     Checking inotify v0.7.1
[INFO] [stderr]     Checking parking_lot v0.11.1
[INFO] [stderr]    Compiling quote v1.0.9
[INFO] [stderr]     Checking mio v0.6.23
[INFO] [stderr]     Checking float-cmp v0.8.0
[INFO] [stderr]     Checking number_prefix v0.2.8
[INFO] [stderr]     Checking regex v1.4.6
[INFO] [stderr]     Checking mio-extras v2.0.6
[INFO] [stderr]     Checking notify v4.0.16
[INFO] [stderr]     Checking console v0.14.1
[INFO] [stderr]     Checking predicates v1.0.7
[INFO] [stderr]     Checking console v0.7.7
[INFO] [stderr]     Checking indicatif v0.10.3
[INFO] [stderr]    Compiling argh_derive v0.1.4
[INFO] [stderr]     Checking argh v0.1.4
[INFO] [stderr]     Checking toml v0.4.10
[INFO] [stderr]     Checking rustlings v4.5.0 (/opt/rustwide/workdir)
[INFO] [stderr]     Checking assert_cmd v0.11.1
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 22.23s
[INFO] running `Command { std: "docker" "inspect" "25c21f9e58e95e054f6b74d62c4a49c5ccdf1d6a0635cf3c3bbee7cc6070252b", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "25c21f9e58e95e054f6b74d62c4a49c5ccdf1d6a0635cf3c3bbee7cc6070252b", kill_on_drop: false }`
[INFO] [stdout] 25c21f9e58e95e054f6b74d62c4a49c5ccdf1d6a0635cf3c3bbee7cc6070252b
[INFO] checking hyhugh/rustlings_answers against try#2d84f2737f3bd9ebfcb07f75aa198d6cf7c715d2 for never-type-fallback-to-never
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Fhyhugh%2Frustlings_answers" "/workspace/builds/worker-7-tc2/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-7-tc2/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/hyhugh/rustlings_answers on toolchain 2d84f2737f3bd9ebfcb07f75aa198d6cf7c715d2
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+2d84f2737f3bd9ebfcb07f75aa198d6cf7c715d2" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/hyhugh/rustlings_answers
[INFO] finished tweaking git repo https://github.com/hyhugh/rustlings_answers
[INFO] tweaked toml for git repo https://github.com/hyhugh/rustlings_answers written to /workspace/builds/worker-7-tc2/source/Cargo.toml
[INFO] crate git repo https://github.com/hyhugh/rustlings_answers already has a lockfile, it will not be regenerated
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+2d84f2737f3bd9ebfcb07f75aa198d6cf7c715d2" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc2/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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+2d84f2737f3bd9ebfcb07f75aa198d6cf7c715d2" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 0626ad5550abcb10a472a19caadb2b2ced76487687b3b53be3c9dd10af4a178e
[INFO] running `Command { std: "docker" "start" "-a" "0626ad5550abcb10a472a19caadb2b2ced76487687b3b53be3c9dd10af4a178e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "0626ad5550abcb10a472a19caadb2b2ced76487687b3b53be3c9dd10af4a178e", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0626ad5550abcb10a472a19caadb2b2ced76487687b3b53be3c9dd10af4a178e", kill_on_drop: false }`
[INFO] [stdout] 0626ad5550abcb10a472a19caadb2b2ced76487687b3b53be3c9dd10af4a178e
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc2/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc2/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@sha256:2788e3201cd34a07e3172128adcd8b3090168a8e3bcc40d7c032b9dda1df7d1c" "/opt/rustwide/cargo-home/bin/cargo" "+2d84f2737f3bd9ebfcb07f75aa198d6cf7c715d2" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 1fdf21297ab174f0290dcd03fd7992481af89e8d8a1938a533214cb583508a16
[INFO] running `Command { std: "docker" "start" "-a" "1fdf21297ab174f0290dcd03fd7992481af89e8d8a1938a533214cb583508a16", kill_on_drop: false }`
[INFO] [stderr]    Compiling libc v0.2.93
[INFO] [stderr]    Compiling proc-macro2 v1.0.26
[INFO] [stderr]    Compiling syn v1.0.70
[INFO] [stderr]    Compiling serde_derive v1.0.125
[INFO] [stderr]    Compiling serde v1.0.125
[INFO] [stderr]     Checking regex-syntax v0.6.23
[INFO] [stderr]     Checking smallvec v1.6.1
[INFO] [stderr]    Compiling ryu v1.0.5
[INFO] [stderr]    Compiling num-traits v0.2.14
[INFO] [stderr]     Checking instant v0.1.9
[INFO] [stderr]     Checking slab v0.4.3
[INFO] [stderr]    Compiling unicode-segmentation v1.7.1
[INFO] [stderr]     Checking lock_api v0.4.3
[INFO] [stderr]    Compiling serde_json v1.0.64
[INFO] [stderr]     Checking lazycell v1.3.0
[INFO] [stderr]    Compiling escargot v0.4.0
[INFO] [stderr]     Checking predicates-core v1.0.2
[INFO] [stderr]     Checking same-file v1.0.6
[INFO] [stderr]    Compiling argh_shared v0.1.4
[INFO] [stderr]     Checking itoa v0.4.7
[INFO] [stderr]     Checking walkdir v2.3.2
[INFO] [stderr]     Checking predicates-tree v1.0.2
[INFO] [stderr]     Checking glob v0.3.0
[INFO] [stderr]    Compiling heck v0.3.2
[INFO] [stderr]    Compiling quote v1.0.9
[INFO] [stderr]     Checking parking_lot_core v0.8.3
[INFO] [stderr]     Checking iovec v0.1.4
[INFO] [stderr]     Checking net2 v0.2.37
[INFO] [stderr]     Checking inotify-sys v0.1.5
[INFO] [stderr]     Checking terminal_size v0.1.16
[INFO] [stderr]     Checking clicolors-control v1.0.1
[INFO] [stderr]     Checking termios v0.3.3
[INFO] [stderr]     Checking atty v0.2.14
[INFO] [stderr]     Checking filetime v0.2.14
[INFO] [stderr]     Checking inotify v0.7.1
[INFO] [stderr]     Checking number_prefix v0.2.8
[INFO] [stderr]     Checking float-cmp v0.8.0
[INFO] [stderr]     Checking parking_lot v0.11.1
[INFO] [stderr]     Checking mio v0.6.23
[INFO] [stderr]     Checking mio-extras v2.0.6
[INFO] [stderr]     Checking notify v4.0.16
[INFO] [stderr]     Checking regex v1.4.6
[INFO] [stderr]    Compiling argh_derive v0.1.4
[INFO] [stderr]     Checking console v0.14.1
[INFO] [stderr]     Checking console v0.7.7
[INFO] [stderr]     Checking predicates v1.0.7
[INFO] [stderr]     Checking indicatif v0.10.3
[INFO] [stderr]     Checking argh v0.1.4
[INFO] [stderr]     Checking toml v0.4.10
[INFO] [stderr]     Checking rustlings v4.5.0 (/opt/rustwide/workdir)
[INFO] [stderr]     Checking assert_cmd v0.11.1
[INFO] [stderr]     Finished `dev` profile [unoptimized + debuginfo] target(s) in 19.37s
[INFO] running `Command { std: "docker" "inspect" "1fdf21297ab174f0290dcd03fd7992481af89e8d8a1938a533214cb583508a16", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "1fdf21297ab174f0290dcd03fd7992481af89e8d8a1938a533214cb583508a16", kill_on_drop: false }`
[INFO] [stdout] 1fdf21297ab174f0290dcd03fd7992481af89e8d8a1938a533214cb583508a16