[INFO] fetching crate sp-rpc 2.0.0-alpha.8...
[INFO] checking sp-rpc-2.0.0-alpha.8 against master#914adf04af1c1a984707f778da3d04590c03d144 for pr-72331
[INFO] extracting crate sp-rpc 2.0.0-alpha.8 into /workspace/builds/worker-6/source
[INFO] validating manifest of crates.io crate sp-rpc 2.0.0-alpha.8 on toolchain 914adf04af1c1a984707f778da3d04590c03d144
[INFO] running `"/workspace/cargo-home/bin/cargo" "+914adf04af1c1a984707f778da3d04590c03d144" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking crates.io crate sp-rpc 2.0.0-alpha.8
[INFO] finished tweaking crates.io crate sp-rpc 2.0.0-alpha.8
[INFO] tweaked toml for crates.io crate sp-rpc 2.0.0-alpha.8 written to /workspace/builds/worker-6/source/Cargo.toml
[INFO] running `"/workspace/cargo-home/bin/cargo" "+914adf04af1c1a984707f778da3d04590c03d144" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/workspace/cargo-home/bin/cargo" "+914adf04af1c1a984707f778da3d04590c03d144" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-6/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" "MAP_USER_ID=0" "-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" "+914adf04af1c1a984707f778da3d04590c03d144" "check" "--frozen" "--all" "--all-targets"`
[INFO] [stderr] WARNING: Your kernel does not support swap limit capabilities or the cgroup is not mounted. Memory limited without swap.
[INFO] [stdout] 2b4604971dc179941c051e2b1e1d0942802c1d41fae92f97040bc57dd1197f31
[INFO] running `"docker" "start" "-a" "2b4604971dc179941c051e2b1e1d0942802c1d41fae92f97040bc57dd1197f31"`
[INFO] [stderr] sudo: setrlimit(RLIMIT_CORE): Operation not permitted
[INFO] [stderr]    Compiling parity-util-mem v0.6.1
[INFO] [stderr]     Checking hash-db v0.15.2
[INFO] [stderr]     Checking libsecp256k1 v0.3.5
[INFO] [stderr]     Checking sp-core v2.0.0-alpha.8
[INFO] [stderr]     Checking sp-rpc v2.0.0-alpha.8 (/opt/rustwide/workdir)
[INFO] [stderr] error[E0433]: failed to resolve: use of undeclared type or module `serde_json`
[INFO] [stderr]   --> src/lib.rs:31:3
[INFO] [stderr]    |
[INFO] [stderr] 31 |         serde_json::from_str::<T>(s).unwrap(),
[INFO] [stderr]    |         ^^^^^^^^^^ use of undeclared type or module `serde_json`
[INFO] [stderr] 
[INFO] [stderr] error[E0433]: failed to resolve: use of undeclared type or module `serde_json`
[INFO] [stderr]   --> src/lib.rs:35:3
[INFO] [stderr]    |
[INFO] [stderr] 35 |         serde_json::to_string(&expected).unwrap(),
[INFO] [stderr]    |         ^^^^^^^^^^ use of undeclared type or module `serde_json`
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to 2 previous errors
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0433`.
[INFO] [stderr] error: could not compile `sp-rpc`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] [stderr] error: build failed
[INFO] running `"docker" "inspect" "2b4604971dc179941c051e2b1e1d0942802c1d41fae92f97040bc57dd1197f31"`
[INFO] running `"docker" "rm" "-f" "2b4604971dc179941c051e2b1e1d0942802c1d41fae92f97040bc57dd1197f31"`
[INFO] [stdout] 2b4604971dc179941c051e2b1e1d0942802c1d41fae92f97040bc57dd1197f31