[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 try#81275a1445c7502a974118e0c69b795ab60be991 for pr-80243
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2Falexclear%2Frust-koans-answers" "/workspace/builds/worker-5/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-5/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/alexclear/rust-koans-answers on toolchain 81275a1445c7502a974118e0c69b795ab60be991
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+81275a1445c7502a974118e0c69b795ab60be991" "read-manifest" "--manifest-path" "Cargo.toml", 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-5/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: "/workspace/cargo-home/bin/cargo" "+81275a1445c7502a974118e0c69b795ab60be991" "fetch" "--locked" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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" "+81275a1445c7502a974118e0c69b795ab60be991" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] df80a38ad84ad56160dd4d499d775ce638564ebdf6baaef7032323c359187e13
[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" "df80a38ad84ad56160dd4d499d775ce638564ebdf6baaef7032323c359187e13", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "df80a38ad84ad56160dd4d499d775ce638564ebdf6baaef7032323c359187e13", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "df80a38ad84ad56160dd4d499d775ce638564ebdf6baaef7032323c359187e13", kill_on_drop: false }`
[INFO] [stdout] df80a38ad84ad56160dd4d499d775ce638564ebdf6baaef7032323c359187e13
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-5/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" "+81275a1445c7502a974118e0c69b795ab60be991" "check" "--frozen" "--all" "--all-targets" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 461801fcdc9a3250da11534a25865bdd0262f48c5b4512808d1b615d232618f0
[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" "461801fcdc9a3250da11534a25865bdd0262f48c5b4512808d1b615d232618f0", 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] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `/opt/rustwide/target/debug/build/koans-87891042a0e7e264/build-script-build` (exit code: 101)
[INFO] [stderr]   --- stderr
[INFO] [stderr]   thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 30, kind: Other, message: "Read-only file system" }', build.rs:7:10
[INFO] [stderr]   stack backtrace:
[INFO] [stderr]      0:     0x5638c5196007 - std::backtrace_rs::backtrace::libunwind::trace::h746c3e9529d524bc
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/../../backtrace/src/backtrace/libunwind.rs:90:5
[INFO] [stderr]      1:     0x5638c5196007 - std::backtrace_rs::backtrace::trace_unsynchronized::h84373278bfb39e0c
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/../../backtrace/src/backtrace/mod.rs:66:5
[INFO] [stderr]      2:     0x5638c5196007 - std::sys_common::backtrace::_print_fmt::h517324efde750597
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/sys_common/backtrace.rs:67:5
[INFO] [stderr]      3:     0x5638c5196007 - <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt::hf594ab77fac89284
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/sys_common/backtrace.rs:46:22
[INFO] [stderr]      4:     0x5638c51ac8ac - core::fmt::write::h3868db8542c90941
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/core/src/fmt/mod.rs:1078:17
[INFO] [stderr]      5:     0x5638c5194262 - std::io::Write::write_fmt::h3f6656f045fa877f
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/io/mod.rs:1519:15
[INFO] [stderr]      6:     0x5638c5197d45 - std::sys_common::backtrace::_print::hda7655c057c24dcc
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/sys_common/backtrace.rs:49:5
[INFO] [stderr]      7:     0x5638c5197d45 - std::sys_common::backtrace::print::h546a6c8431d46287
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/sys_common/backtrace.rs:36:9
[INFO] [stderr]      8:     0x5638c5197d45 - std::panicking::default_hook::{{closure}}::h006dd083853faf51
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/panicking.rs:208:50
[INFO] [stderr]      9:     0x5638c519789a - std::panicking::default_hook::hf0f9afb1017317fc
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/panicking.rs:225:9
[INFO] [stderr]     10:     0x5638c51984e1 - std::panicking::rust_panic_with_hook::hb7a19826c029b1d6
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/panicking.rs:591:17
[INFO] [stderr]     11:     0x5638c5198027 - std::panicking::begin_panic_handler::{{closure}}::hde71edcd925d0c5e
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/panicking.rs:497:13
[INFO] [stderr]     12:     0x5638c51964cc - std::sys_common::backtrace::__rust_end_short_backtrace::h8a3c7d6cea578919
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/sys_common/backtrace.rs:141:18
[INFO] [stderr]     13:     0x5638c5197f89 - rust_begin_unwind
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/panicking.rs:493:5
[INFO] [stderr]     14:     0x5638c51abc81 - core::panicking::panic_fmt::h20225113c4a2f8fd
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/core/src/panicking.rs:92:14
[INFO] [stderr]     15:     0x5638c51abaa3 - core::option::expect_none_failed::hc6d6d4cea4fdc285
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/core/src/option.rs:1268:5
[INFO] [stderr]     16:     0x5638c517fbbb - core::result::Result<T,E>::unwrap::h83dc7129447c6afe
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/core/src/result.rs:973:23
[INFO] [stderr]     17:     0x5638c517fa57 - build_script_build::main::h2d5c5168c5a1a5a6
[INFO] [stderr]                                  at /opt/rustwide/workdir/build.rs:4:5
[INFO] [stderr]     18:     0x5638c517f6db - core::ops::function::FnOnce::call_once::hde5baf7d4097ac32
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/core/src/ops/function.rs:227:5
[INFO] [stderr]     19:     0x5638c517f63e - std::sys_common::backtrace::__rust_begin_short_backtrace::h188b31dc0305d79f
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/sys_common/backtrace.rs:125:18
[INFO] [stderr]     20:     0x5638c517f9b1 - std::rt::lang_start::{{closure}}::h27bd22285a5ca98e
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/rt.rs:66:18
[INFO] [stderr]     21:     0x5638c5198907 - core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once::h54c39b9b8451875a
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/core/src/ops/function.rs:259:13
[INFO] [stderr]     22:     0x5638c5198907 - std::panicking::try::do_call::hcdfba51a06e21b42
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/panicking.rs:379:40
[INFO] [stderr]     23:     0x5638c5198907 - std::panicking::try::h77386c66889b2066
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/panicking.rs:343:19
[INFO] [stderr]     24:     0x5638c5198907 - std::panic::catch_unwind::hc55a0d8aadca44f0
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/panic.rs:396:14
[INFO] [stderr]     25:     0x5638c5198907 - std::rt::lang_start_internal::h97dca9624db2aa85
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/rt.rs:51:25
[INFO] [stderr]     26:     0x5638c517f987 - std::rt::lang_start::h057e725eda069a20
[INFO] [stderr]                                  at /rustc/81275a1445c7502a974118e0c69b795ab60be991/library/std/src/rt.rs:65:5
[INFO] [stderr]     27:     0x5638c517fa9a - main
[INFO] [stderr]     28:     0x7fe0d1fc90b3 - __libc_start_main
[INFO] [stderr]     29:     0x5638c517f09e - _start
[INFO] [stderr]     30:                0x0 - <unknown>
[INFO] running `Command { std: "docker" "inspect" "461801fcdc9a3250da11534a25865bdd0262f48c5b4512808d1b615d232618f0", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "461801fcdc9a3250da11534a25865bdd0262f48c5b4512808d1b615d232618f0", kill_on_drop: false }`
[INFO] [stdout] 461801fcdc9a3250da11534a25865bdd0262f48c5b4512808d1b615d232618f0