[INFO] fetching crate rsflex 0.3.0...
[INFO] testing rsflex-0.3.0 against 1.90.0 for beta-1.91-3
[INFO] extracting crate rsflex 0.3.0 into /workspace/builds/worker-7-tc1/source
[INFO] started tweaking crates.io crate rsflex 0.3.0
[INFO] finished tweaking crates.io crate rsflex 0.3.0
[INFO] tweaked toml for crates.io crate rsflex 0.3.0 written to /workspace/builds/worker-7-tc1/source/Cargo.toml
[INFO] validating manifest of crates.io crate rsflex 0.3.0 on toolchain 1.90.0
[INFO] running `Command { std: CARGO_HOME="/workspace/cargo-home" RUSTUP_HOME="/workspace/rustup-home" "/workspace/cargo-home/bin/cargo" "+1.90.0" "metadata" "--manifest-path" "Cargo.toml" "--no-deps", kill_on_drop: false }`
[INFO] crate crates.io crate rsflex 0.3.0 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" "+1.90.0" "fetch" "--manifest-path" "Cargo.toml", kill_on_drop: false }`
[INFO] [stderr]     Updating crates.io index
[INFO] [stderr]  Downloading crates ...
[INFO] [stderr]   Downloaded cc v1.0.66
[INFO] [stderr]   Downloaded cmd_lib_core v0.1.0
[INFO] [stderr]   Downloaded hermit-abi v0.1.18
[INFO] [stderr]   Downloaded mimalloc v0.1.24
[INFO] [stderr]   Downloaded cmd_lib v0.8.5
[INFO] [stderr]   Downloaded cmd_lib_macros v0.1.0
[INFO] [stderr]   Downloaded libc v0.2.86
[INFO] [stderr]   Downloaded libmimalloc-sys v0.1.20
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+1.90.0" "metadata" "--no-deps" "--format-version=1", kill_on_drop: false }`
[INFO] [stdout] 180315496e1aab4d42da1264dd76e75564ed9036ae1a8d258a2b44915cd294ab
[INFO] running `Command { std: "docker" "start" "-a" "180315496e1aab4d42da1264dd76e75564ed9036ae1a8d258a2b44915cd294ab", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "inspect" "180315496e1aab4d42da1264dd76e75564ed9036ae1a8d258a2b44915cd294ab", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "180315496e1aab4d42da1264dd76e75564ed9036ae1a8d258a2b44915cd294ab", kill_on_drop: false }`
[INFO] [stdout] 180315496e1aab4d42da1264dd76e75564ed9036ae1a8d258a2b44915cd294ab
[INFO] running `Command { std: "docker" "create" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-tc1/target:/opt/rustwide/target:rw,Z" "-v" "/var/lib/crater-agent-workspace/builds/worker-7-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=warn" "-e" "RUSTDOCFLAGS=--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:e90291280db7d1fac5b66fc6dad9f9662629e7365a55743daf9bdf73ebc4ea79" "/opt/rustwide/cargo-home/bin/cargo" "+1.90.0" "build" "--frozen" "--message-format=json", kill_on_drop: false }`
[INFO] [stdout] 8db1acdd5442c55b2d891f435faef4cb43d3bde192f6b4b5f75d979d3a92c2e2
[INFO] running `Command { std: "docker" "start" "-a" "8db1acdd5442c55b2d891f435faef4cb43d3bde192f6b4b5f75d979d3a92c2e2", kill_on_drop: false }`
[INFO] [stderr]    Compiling cc v1.0.66
[INFO] [stderr]    Compiling proc-macro2 v1.0.24
[INFO] [stderr]    Compiling libc v0.2.86
[INFO] [stderr]    Compiling cmd_lib_core v0.1.0
[INFO] [stderr]    Compiling once_cell v1.5.2
[INFO] [stderr]    Compiling regex-syntax v0.6.22
[INFO] [stderr]    Compiling thread_local v1.1.3
[INFO] [stderr]    Compiling cmake v0.1.45
[INFO] [stderr]    Compiling quote v1.0.9
[INFO] [stderr]    Compiling atty v0.2.14
[INFO] [stderr]    Compiling libmimalloc-sys v0.1.20
[INFO] [stderr]    Compiling colored v2.0.0
[INFO] [stderr]    Compiling cmd_lib_macros v0.1.0
[INFO] [stdout] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stdout]  --> /opt/rustwide/cargo-home/registry/src/index.crates.io-1949cf8c6b5b557f/cmd_lib_macros-0.1.0/src/lib.rs:1:1
[INFO] [stdout]   |
[INFO] [stdout] 1 | #![feature(proc_macro_span)]
[INFO] [stdout]   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
[INFO] [stdout] 
[INFO] [stdout] 
[INFO] [stdout] For more information about this error, try `rustc --explain E0554`.
[INFO] [stdout] 
[INFO] [stderr] error: could not compile `cmd_lib_macros` (lib) due to 1 previous error
[INFO] [stderr] warning: build failed, waiting for other jobs to finish...
[INFO] running `Command { std: "docker" "inspect" "8db1acdd5442c55b2d891f435faef4cb43d3bde192f6b4b5f75d979d3a92c2e2", kill_on_drop: false }`
[INFO] running `Command { std: "docker" "rm" "-f" "8db1acdd5442c55b2d891f435faef4cb43d3bde192f6b4b5f75d979d3a92c2e2", kill_on_drop: false }`
[INFO] [stdout] 8db1acdd5442c55b2d891f435faef4cb43d3bde192f6b4b5f75d979d3a92c2e2