[INFO] updating cached repository https://github.com/mattdeboard/prepend_line
[INFO] running `"git" "-c" "credential.helper=" "-c" "credential.helper=/mnt/big/crater/work/cargo-home/bin/git-credential-null" "-c" "remote.origin.fetch=refs/heads/*:refs/heads/*" "fetch" "origin" "--force" "--prune"`
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] e4dc1c7a8266c455ef3c617f4a8b37bd0b4b676c
[INFO] checking mattdeboard/prepend_line against try#e689e5eaefe96e6dc3ed5bb629c521b7d207aff7 for pr-64398
[INFO] running `"git" "clone" "work/cache/git-repos/https%3A%2F%2Fgithub.com%2Fmattdeboard%2Fprepend_line" "work/builds/worker-6/source"`
[INFO] [stderr] Cloning into 'work/builds/worker-6/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/mattdeboard/prepend_line on toolchain e689e5eaefe96e6dc3ed5bb629c521b7d207aff7-alt
[INFO] running `"/mnt/big/crater/work/cargo-home/bin/cargo" "+e689e5eaefe96e6dc3ed5bb629c521b7d207aff7-alt" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking git repo https://github.com/mattdeboard/prepend_line
[INFO] finished tweaking git repo https://github.com/mattdeboard/prepend_line
[INFO] tweaked toml for git repo https://github.com/mattdeboard/prepend_line written to work/builds/worker-6/source/Cargo.toml
[INFO] crate git repo https://github.com/mattdeboard/prepend_line already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/cargo-home/bin/cargo" "+e689e5eaefe96e6dc3ed5bb629c521b7d207aff7-alt" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/builds/worker-6/target:/opt/rustwide/target:rw,Z" "-v" "/mnt/big/crater/work/builds/worker-6/source:/opt/rustwide/workdir:ro,Z" "-v" "/mnt/big/crater/work/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/rustup-home:/opt/rustwide/rustup-home:ro,Z" "-e" "SOURCE_DIR=/opt/rustwide/workdir" "-e" "MAP_USER_ID=1000" "-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" "--network" "none" "rustops/crates-build-env" "/opt/rustwide/cargo-home/bin/cargo" "+e689e5eaefe96e6dc3ed5bb629c521b7d207aff7-alt" "check" "--frozen" "--all" "--all-targets"`
[INFO] [stdout] 3a4c6e09e1408daac26312d5720262646420df5a7a8afe653a5b889b44df975a
[INFO] running `"docker" "start" "-a" "3a4c6e09e1408daac26312d5720262646420df5a7a8afe653a5b889b44df975a"`
[INFO] [stderr]    Compiling proc-macro2 v0.4.12
[INFO] [stderr]    Compiling wasm-bindgen-shared v0.2.16
[INFO] [stderr]    Compiling log v0.4.3
[INFO] [stderr]    Compiling ryu v0.2.3
[INFO] [stderr]     Checking uuid v0.1.18
[INFO] [stderr]     Checking regex v1.0.2
[INFO] [stderr]    Compiling serde_json v1.0.26
[INFO] [stderr]     Checking mktemp v0.3.1
[INFO] [stderr] error[E0658]: use of unstable library feature 'proc_macro_def_site'
[INFO] [stderr]    --> /opt/rustwide/cargo-home/registry/src/github.com-1ecc6299db9ec823/proc-macro2-0.4.12/src/unstable.rs:346:27
[INFO] [stderr]     |
[INFO] [stderr] 346 |             Span::Nightly(proc_macro::Span::def_site())
[INFO] [stderr]     |                           ^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stderr]     |
[INFO] [stderr]     = note: for more information, see https://github.com/rust-lang/rust/issues/54724
[INFO] [stderr]     = help: add `#![feature(proc_macro_def_site)]` to the crate attributes to enable
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0658`.
[INFO] [stderr] error: Could not compile `proc-macro2`.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "3a4c6e09e1408daac26312d5720262646420df5a7a8afe653a5b889b44df975a"`
[INFO] running `"docker" "rm" "-f" "3a4c6e09e1408daac26312d5720262646420df5a7a8afe653a5b889b44df975a"`
[INFO] [stdout] 3a4c6e09e1408daac26312d5720262646420df5a7a8afe653a5b889b44df975a