[INFO] updating cached repository gyng/midcat
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/gyng/midcat
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/gyng/midcat" "work/ex/beta-1.38-1/sources/1.37.0/gh/gyng/midcat"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/gyng/midcat'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/gyng/midcat" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/gyng/midcat"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/gyng/midcat'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] 77677cdabbb18277e6046fc1450d49895c30c61e
[INFO] sha for GitHub repo gyng/midcat: 77677cdabbb18277e6046fc1450d49895c30c61e
[INFO] validating manifest of gyng/midcat on toolchain 1.37.0
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] validating manifest of gyng/midcat on toolchain beta-2019-08-13
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "read-manifest" "--manifest-path" "Cargo.toml"`
[INFO] started frobbing gyng/midcat
[INFO] finished frobbing gyng/midcat
[INFO] frobbed toml for gyng/midcat written to work/ex/beta-1.38-1/sources/1.37.0/gh/gyng/midcat/Cargo.toml
[INFO] started frobbing gyng/midcat
[INFO] finished frobbing gyng/midcat
[INFO] frobbed toml for gyng/midcat written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/gyng/midcat/Cargo.toml
[INFO] crate gyng/midcat already has a lockfile, it will not be regenerated
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "fetch" "--locked" "--manifest-path" "Cargo.toml"`
[INFO] testing gyng/midcat against 1.37.0 for beta-1.38-1
[INFO] running `"docker" "create" "-v" "/mnt/big/crater/work/local/target-dirs/beta-1.38-1/worker-6/1.37.0:/opt/crater/target:rw,Z" "-v" "/mnt/big/crater/work/ex/beta-1.38-1/sources/1.37.0/gh/gyng/midcat:/opt/crater/workdir:ro,Z" "-v" "/mnt/big/crater/work/local/cargo-home:/opt/crater/cargo-home:ro,Z" "-v" "/mnt/big/crater/work/local/rustup-home:/opt/crater/rustup-home:ro,Z" "-e" "USER_ID=1000" "-e" "SOURCE_DIR=/opt/crater/workdir" "-e" "MAP_USER_ID=1000" "-e" "CARGO_TARGET_DIR=/opt/crater/target" "-e" "CARGO_INCREMENTAL=0" "-e" "RUST_BACKTRACE=full" "-e" "RUSTFLAGS=--cap-lints=warn" "-e" "CARGO_HOME=/opt/crater/cargo-home" "-e" "RUSTUP_HOME=/opt/crater/rustup-home" "-w" "/opt/crater/workdir" "-m" "1536M" "--network" "none" "rustops/crates-build-env" "/opt/crater/cargo-home/bin/cargo" "+1.37.0" "build" "--frozen"`
[INFO] [stdout] b42bf26b23c2cc7baee1f1b6e4ac544de23fcde4a7977b7a67f85f10babd9bc1
[INFO] running `"docker" "start" "-a" "b42bf26b23c2cc7baee1f1b6e4ac544de23fcde4a7977b7a67f85f10babd9bc1"`
[INFO] [stderr]     Blocking waiting for file lock on package cache
[INFO] [stderr]    Compiling num-bigint v0.2.1
[INFO] [stderr]    Compiling num-integer v0.1.39
[INFO] [stderr]    Compiling num-complex v0.2.1
[INFO] [stderr]    Compiling rand v0.5.5
[INFO] [stderr]    Compiling alsa-sys v0.1.1
[INFO] [stderr]    Compiling docopt v0.8.1
[INFO] [stderr]    Compiling cpal v0.4.5
[INFO] [stderr]    Compiling num-iter v0.1.37
[INFO] [stderr]    Compiling num-rational v0.2.1
[INFO] [stderr]    Compiling num v0.2.0
[INFO] [stderr]    Compiling synthrs v0.1.0 (https://github.com/gyng/synthrs?rev=a067f2bee46e5f8593003dc4ad5b6df97bdb3898#a067f2be)
[INFO] [stderr] error[E0554]: #![feature] may not be used on the stable release channel
[INFO] [stderr]  --> /opt/crater/cargo-home/git/checkouts/synthrs-a4b8c03c849616c3/a067f2b/src/lib.rs:1:1
[INFO] [stderr]   |
[INFO] [stderr] 1 | #![feature(fn_traits, unboxed_closures)]
[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 `synthrs`.
[INFO] [stderr] 
[INFO] [stderr] To learn more, run the command again with --verbose.
[INFO] running `"docker" "inspect" "b42bf26b23c2cc7baee1f1b6e4ac544de23fcde4a7977b7a67f85f10babd9bc1"`
[INFO] running `"docker" "rm" "-f" "b42bf26b23c2cc7baee1f1b6e4ac544de23fcde4a7977b7a67f85f10babd9bc1"`
[INFO] [stdout] b42bf26b23c2cc7baee1f1b6e4ac544de23fcde4a7977b7a67f85f10babd9bc1