[INFO] updating cached repository japaric/zen
[INFO] running `"git" "fetch" "--all"`
[INFO] [stdout] Fetching origin
[INFO] [stderr] From git://github.com/japaric/zen
[INFO] [stderr]  * branch            HEAD       -> FETCH_HEAD
[INFO] running `"git" "clone" "work/cache/sources/gh/japaric/zen" "work/ex/beta-1.38-1/sources/1.37.0/gh/japaric/zen"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/1.37.0/gh/japaric/zen'...
[INFO] [stderr] done.
[INFO] running `"git" "clone" "work/cache/sources/gh/japaric/zen" "work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/japaric/zen"`
[INFO] [stderr] Cloning into 'work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/japaric/zen'...
[INFO] [stderr] done.
[INFO] running `"git" "rev-parse" "HEAD"`
[INFO] [stdout] b1d056a71440115f32123e364a39166e2399882e
[INFO] sha for GitHub repo japaric/zen: b1d056a71440115f32123e364a39166e2399882e
[INFO] validating manifest of japaric/zen 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 japaric/zen 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 japaric/zen
[INFO] finished frobbing japaric/zen
[INFO] frobbed toml for japaric/zen written to work/ex/beta-1.38-1/sources/1.37.0/gh/japaric/zen/Cargo.toml
[INFO] started frobbing japaric/zen
[INFO] finished frobbing japaric/zen
[INFO] frobbed toml for japaric/zen written to work/ex/beta-1.38-1/sources/beta-2019-08-13/gh/japaric/zen/Cargo.toml
[INFO] crate japaric/zen 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] [stderr] error: failed to run `rustc` to learn about target-specific information
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `rustc - --crate-name ___ --print=file-names -C link-arg=-Tlink.x -C linker=arm-none-eabi-ld -Z linker-flavor=ld -Z thinlto=no --target thumbv7m-none-eabi --crate-type bin --crate-type rlib --crate-type dylib --crate-type cdylib --crate-type staticlib --crate-type proc-macro` (exit code: 1)
[INFO] [stderr] --- stderr
[INFO] [stderr] error: the option `Z` is only accepted on the nightly compiler
[INFO] [stderr] 
[INFO] [stderr] 
[ERROR] this task or one of its parent failed!
[ERROR] command `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "fetch" "--locked" "--manifest-path" "Cargo.toml"` failed