[INFO] cloning repository https://github.com/alexclear/rust-koans-answers
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/alexclear/rust-koans-answers" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Falexclear%2Frust-koans-answers", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Falexclear%2Frust-koans-answers'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 89e124c056c315e10c6d5ab8548902c0cfc64be5
[INFO] checking alexclear/rust-koans-answers against master#af4a5a13a15fa0c60e06321077ef452f769b42fd for pr-122960-4
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Falexclear%2Frust-koans-answers" "/workspace/builds/worker-1-tc1/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-1-tc1/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/alexclear/rust-koans-answers on toolchain af4a5a13a15fa0c60e06321077ef452f769b42fd
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+af4a5a13a15fa0c60e06321077ef452f769b42fd" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/alexclear/rust-koans-answers
[INFO] finished tweaking git repo https://github.com/alexclear/rust-koans-answers
[INFO] tweaked toml for git repo https://github.com/alexclear/rust-koans-answers written to /workspace/builds/worker-1-tc1/source/Cargo.toml
[INFO] crate git repo https://github.com/alexclear/rust-koans-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" "+af4a5a13a15fa0c60e06321077ef452f769b42fd" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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" "+af4a5a13a15fa0c60e06321077ef452f769b42fd" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 0b4e74e39921097faa6ad811767593508300b37a7f7990a7f5c58f83ee9ad0c3
[INFO] running `Command { std: "docker" "start" "-a" "0b4e74e39921097faa6ad811767593508300b37a7f7990a7f5c58f83ee9ad0c3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "0b4e74e39921097faa6ad811767593508300b37a7f7990a7f5c58f83ee9ad0c3", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "0b4e74e39921097faa6ad811767593508300b37a7f7990a7f5c58f83ee9ad0c3", kill_on_drop: false }`
[INFO] [stdout] 0b4e74e39921097faa6ad811767593508300b37a7f7990a7f5c58f83ee9ad0c3
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-1-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=allow" "-e" "RUSTDOCFLAGS=--cap-lints=allow" "-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" "+af4a5a13a15fa0c60e06321077ef452f769b42fd" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 16ed4498ca5b33c57ab812551468a87c29305483051f21211b01e4f90ebcf318
[INFO] running `Command { std: "docker" "start" "-a" "16ed4498ca5b33c57ab812551468a87c29305483051f21211b01e4f90ebcf318", kill_on_drop: false }`
[INFO] [stderr]    Compiling koans v0.2.0 (/opt/rustwide/workdir)
[INFO] [stderr] error: failed to run custom build command for `koans v0.2.0 (/opt/rustwide/workdir)`
[INFO] [stderr] note: To improve backtraces for build dependencies, set the CARGO_PROFILE_DEV_BUILD_OVERRIDE_DEBUG=true environment variable to enable debug information generation.
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `/opt/rustwide/target/debug/build/koans-db4b646b69e25643/build-script-build` (exit status: 101)
[INFO] [stderr]   --- stderr
[INFO] [stderr]   thread 'main' panicked at build.rs:7:10:
[INFO] [stderr]   called `Result::unwrap()` on an `Err` value: Os { code: 30, kind: ReadOnlyFilesystem, message: "Read-only file system" }
[INFO] [stderr]   stack backtrace:
[INFO] [stderr]      0:     0x55c85dbd6d55 - std::backtrace_rs::backtrace::libunwind::trace::hb0d415bcff8c04ff
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/../../backtrace/src/backtrace/libunwind.rs:105:5
[INFO] [stderr]      1:     0x55c85dbd6d55 - std::backtrace_rs::backtrace::trace_unsynchronized::hd3beb7af6a65b2fb
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
[INFO] [stderr]      2:     0x55c85dbd6d55 - std::sys_common::backtrace::_print_fmt::hb94d89680d7f5d1c
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/sys_common/backtrace.rs:68:5
[INFO] [stderr]      3:     0x55c85dbd6d55 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::h42d21e2ba62fd274
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/sys_common/backtrace.rs:44:22
[INFO] [stderr]      4:     0x55c85dbf452b - core::fmt::rt::Argument::fmt::h8932bbbd2b9c37fe
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/core/src/fmt/rt.rs:142:9
[INFO] [stderr]      5:     0x55c85dbf452b - core::fmt::write::h672f14b769052340
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/core/src/fmt/mod.rs:1153:17
[INFO] [stderr]      6:     0x55c85dbd4fbf - std::io::Write::write_fmt::h4d626b1d019eca5c
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/io/mod.rs:1843:15
[INFO] [stderr]      7:     0x55c85dbd6b2e - std::sys_common::backtrace::_print::h745e446c2e03c5ca
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/sys_common/backtrace.rs:47:5
[INFO] [stderr]      8:     0x55c85dbd6b2e - std::sys_common::backtrace::print::hf0f0fa4fb70dca2c
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/sys_common/backtrace.rs:34:9
[INFO] [stderr]      9:     0x55c85dbd7f99 - std::panicking::default_hook::{{closure}}::h607769b198639ae5
[INFO] [stderr]     10:     0x55c85dbd7d03 - std::panicking::default_hook::h1e5811a5a9298ba1
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/panicking.rs:292:9
[INFO] [stderr]     11:     0x55c85dbd8434 - std::panicking::rust_panic_with_hook::hd0c5dc40875c06ef
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/panicking.rs:789:13
[INFO] [stderr]     12:     0x55c85dbd8316 - std::panicking::begin_panic_handler::{{closure}}::hde3f6d4bced89f43
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/panicking.rs:658:13
[INFO] [stderr]     13:     0x55c85dbd7219 - std::sys_common::backtrace::__rust_end_short_backtrace::h88e846e54ebde2e3
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/sys_common/backtrace.rs:171:18
[INFO] [stderr]     14:     0x55c85dbd8047 - rust_begin_unwind
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/panicking.rs:646:5
[INFO] [stderr]     15:     0x55c85dbbbb76 - core::panicking::panic_fmt::h5ffad3fb9ad671e0
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/core/src/panicking.rs:72:14
[INFO] [stderr]     16:     0x55c85dbbbf86 - core::result::unwrap_failed::hb58638a1c26ab909
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/core/src/result.rs:1654:5
[INFO] [stderr]     17:     0x55c85dbbcc0f - build_script_build::main::hf9d0a675df213a83
[INFO] [stderr]     18:     0x55c85dbbc7d3 - core::ops::function::FnOnce::call_once::h3068fb6a9168f3ba
[INFO] [stderr]     19:     0x55c85dbbc236 - std::sys_common::backtrace::__rust_begin_short_backtrace::h021e542d76d2a879
[INFO] [stderr]     20:     0x55c85dbbc799 - std::rt::lang_start::{{closure}}::he37a17c71028de89
[INFO] [stderr]     21:     0x55c85dbd2e81 - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once::hf24a18568366726b
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/core/src/ops/function.rs:284:13
[INFO] [stderr]     22:     0x55c85dbd2e81 - std::panicking::try::do_call::hfe98fb6a5c700fa1
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/panicking.rs:553:40
[INFO] [stderr]     23:     0x55c85dbd2e81 - std::panicking::try::h887aaa509ba266ad
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/panicking.rs:517:19
[INFO] [stderr]     24:     0x55c85dbd2e81 - std::panic::catch_unwind::hdb24f00ea5a307a8
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/panic.rs:146:14
[INFO] [stderr]     25:     0x55c85dbd2e81 - std::rt::lang_start_internal::{{closure}}::hacbffc0b2f55d28c
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/rt.rs:148:48
[INFO] [stderr]     26:     0x55c85dbd2e81 - std::panicking::try::do_call::hc810c59098be8c17
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/panicking.rs:553:40
[INFO] [stderr]     27:     0x55c85dbd2e81 - std::panicking::try::h0d072b82be5f3f03
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/panicking.rs:517:19
[INFO] [stderr]     28:     0x55c85dbd2e81 - std::panic::catch_unwind::hb0e7e36556665803
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/panic.rs:146:14
[INFO] [stderr]     29:     0x55c85dbd2e81 - std::rt::lang_start_internal::h4207974af80a0725
[INFO] [stderr]                                  at /rustc/af4a5a13a15fa0c60e06321077ef452f769b42fd/library/std/src/rt.rs:148:20
[INFO] [stderr]     30:     0x55c85dbbc777 - std::rt::lang_start::h755a4ee1c4bf478e
[INFO] [stderr]     31:     0x55c85dbbcc75 - main
[INFO] [stderr]     32:     0x7f4c0c862d90 - <unknown>
[INFO] [stderr]     33:     0x7f4c0c862e40 - __libc_start_main
[INFO] [stderr]     34:     0x55c85dbbc165 - _start
[INFO] [stderr]     35:                0x0 - <unknown>
[INFO] running `Command { std: "docker" "inspect" "16ed4498ca5b33c57ab812551468a87c29305483051f21211b01e4f90ebcf318", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "16ed4498ca5b33c57ab812551468a87c29305483051f21211b01e4f90ebcf318", kill_on_drop: false }`
[INFO] [stdout] 16ed4498ca5b33c57ab812551468a87c29305483051f21211b01e4f90ebcf318