[INFO] updating cached repository https://github.com/zjhken/MioPractice
[INFO] running `"git" "-c" "credential.helper=" "-c" "credential.helper=/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] b7e077633c9c64e7342ee2e473eea1a4421e8a49
[INFO] testing zjhken/MioPractice against 1.38.0 for beta-1.39-1
[INFO] running `"git" "clone" "work/cache/git-repos/https%3A%2F%2Fgithub.com%2Fzjhken%2FMioPractice" "work/builds/worker-7/source"`
[INFO] [stderr] Cloning into 'work/builds/worker-7/source'...
[INFO] [stderr] done.
[INFO] validating manifest of git repo https://github.com/zjhken/MioPractice on toolchain 1.38.0
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started tweaking git repo https://github.com/zjhken/MioPractice
[INFO] finished tweaking git repo https://github.com/zjhken/MioPractice
[INFO] tweaked toml for git repo https://github.com/zjhken/MioPractice written to work/builds/worker-7/source/Cargo.toml
[INFO] crate git repo https://github.com/zjhken/MioPractice already has a lockfile, it will not be regenerated
[INFO] running `"/big/crater/work/cargo-home/bin/cargo" "+1.38.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"docker" "create" "-v" "/big/crater/work/builds/worker-7/target:/opt/rustwide/target:rw,Z" "-v" "/big/crater/work/builds/worker-7/source:/opt/rustwide/workdir:ro,Z" "-v" "/big/crater/work/cargo-home:/opt/rustwide/cargo-home:ro,Z" "-v" "/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=warn" "-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" "+1.38.0" "build" "--frozen"`
[INFO] [stdout] d8733d94756d8cf30d5a8d0ebbd34c9fc23c4ac987f85302303c7cbbc69e4eaa
[INFO] running `"docker" "start" "-a" "d8733d94756d8cf30d5a8d0ebbd34c9fc23c4ac987f85302303c7cbbc69e4eaa"`
[INFO] [stderr]    Compiling cfg-if v0.1.3
[INFO] [stderr]    Compiling libc v0.2.42
[INFO] [stderr]    Compiling slab v0.4.0
[INFO] [stderr]    Compiling lazycell v0.6.0
[INFO] [stderr]    Compiling log v0.4.4
[INFO] [stderr]    Compiling net2 v0.2.32
[INFO] [stderr]    Compiling time v0.1.40
[INFO] [stderr]    Compiling iovec v0.1.2
[INFO] [stderr]    Compiling mio v0.6.14
[INFO] [stderr]    Compiling simple_logger v0.5.0
[INFO] [stderr]    Compiling MioPractice v0.1.0 (/opt/rustwide/workdir)
[INFO] [stderr] error[E0554]: `#![feature]` may not be used on the stable release channel
[INFO] [stderr]  --> src/lib.rs:2:1
[INFO] [stderr]   |
[INFO] [stderr] 2 | #![feature(nll)]
[INFO] [stderr]   | ^^^^^^^^^^^^^^^^
[INFO] [stderr] 
[INFO] [stderr] error: aborting due to previous error
[INFO] [stderr] 
[INFO] [stderr] For more information about this error, try `rustc --explain E0554`.
[INFO] [stderr] error: Could not compile `MioPractice`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "d8733d94756d8cf30d5a8d0ebbd34c9fc23c4ac987f85302303c7cbbc69e4eaa"`
[INFO] running `"docker" "rm" "-f" "d8733d94756d8cf30d5a8d0ebbd34c9fc23c4ac987f85302303c7cbbc69e4eaa"`
[INFO] [stdout] d8733d94756d8cf30d5a8d0ebbd34c9fc23c4ac987f85302303c7cbbc69e4eaa