[INFO] cloning repository https://github.com/EliasHolzmann/include_optional
[INFO] running `Command { std: "git" "-c" "credential.helper=" "-c" "credential.helper=/workspace/cargo-home/bin/git-credential-null" "clone" "--bare" "https://github.com/EliasHolzmann/include_optional" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FEliasHolzmann%2Finclude_optional", kill_on_drop: false }`
[INFO] [stderr] Cloning into bare repository '/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FEliasHolzmann%2Finclude_optional'...
[INFO] running `Command { std: "git" "rev-parse" "HEAD", kill_on_drop: false }`
[INFO] [stdout] 301f14a169fe0ce76450629ff2d0b5dda4c4af8d
[INFO] testing EliasHolzmann/include_optional against 1.55.0 for beta-1.56-1
[INFO] running `Command { std: "git" "clone" "/workspace/cache/git-repos/https%3A%2F%2Fgithub.com%2FEliasHolzmann%2Finclude_optional" "/workspace/builds/worker-43/source", kill_on_drop: false }`
[INFO] [stderr] Cloning into '/workspace/builds/worker-43/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/EliasHolzmann/include_optional on toolchain 1.55.0
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] started tweaking git repo https://github.com/EliasHolzmann/include_optional
[INFO] finished tweaking git repo https://github.com/EliasHolzmann/include_optional
[INFO] tweaked toml for git repo https://github.com/EliasHolzmann/include_optional written to /workspace/builds/worker-43/source/Cargo.toml
[INFO] crate git repo https://github.com/EliasHolzmann/include_optional already has a lockfile, it will not be regenerated
[INFO] running `Command { std: "/workspace/cargo-home/bin/cargo" "+1.55.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-43/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-43/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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] fa031dd51314566b1c60e06e83c10f8649da364f92d78b9731167fae5aaa3dd2
[INFO] running `Command { std: "docker" "start" "-a" "fa031dd51314566b1c60e06e83c10f8649da364f92d78b9731167fae5aaa3dd2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "fa031dd51314566b1c60e06e83c10f8649da364f92d78b9731167fae5aaa3dd2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "fa031dd51314566b1c60e06e83c10f8649da364f92d78b9731167fae5aaa3dd2", kill_on_drop: false }`
[INFO] [stdout] fa031dd51314566b1c60e06e83c10f8649da364f92d78b9731167fae5aaa3dd2
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-43/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-43/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=warn" "-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:a89201d6b5b9fd45c15d5952ece0a0129e7e80cb26ec023fd59cf09bc26f1604" "/opt/rustwide/cargo-home/bin/cargo" "+1.55.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] ddb7e679065685867a70b5fc3ef7b728762e3e3e7a40e114a409ddbf31882cdd
[INFO] running `Command { std: "docker" "start" "-a" "ddb7e679065685867a70b5fc3ef7b728762e3e3e7a40e114a409ddbf31882cdd", kill_on_drop: false }`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling proc-macro2 v1.0.28
[INFO] [stderr]    Compiling unicode-xid v0.2.2
[INFO] [stderr]    Compiling syn v1.0.74
[INFO] [stderr]    Compiling quote v1.0.9
[INFO] [stderr]    Compiling include_optional v1.0.1 (/opt/rustwide/workdir)
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> src/lib.rs:4:1
[INFO] [stdout]   |
[INFO] [stdout] 4 | #![feature(proc_macro_span, path_try_exists)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] error: aborting due to previous error
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `include_optional` due to 2 previous errors
[INFO] running `Command { std: "docker" "inspect" "ddb7e679065685867a70b5fc3ef7b728762e3e3e7a40e114a409ddbf31882cdd", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "ddb7e679065685867a70b5fc3ef7b728762e3e3e7a40e114a409ddbf31882cdd", kill_on_drop: false }`
[INFO] [stdout] ddb7e679065685867a70b5fc3ef7b728762e3e3e7a40e114a409ddbf31882cdd