[INFO] crate stm32f042 0.6.3 is already in cache
[INFO] extracting crate stm32f042 0.6.3 into work/ex/beta-1.38-1/sources/1.37.0/reg/stm32f042/0.6.3
[INFO] extracting crate stm32f042 0.6.3 into work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/stm32f042/0.6.3
[INFO] validating manifest of stm32f042-0.6.3 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 stm32f042-0.6.3 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 stm32f042-0.6.3
[INFO] finished frobbing stm32f042-0.6.3
[INFO] frobbed toml for stm32f042-0.6.3 written to work/ex/beta-1.38-1/sources/1.37.0/reg/stm32f042/0.6.3/Cargo.toml
[INFO] started frobbing stm32f042-0.6.3
[INFO] finished frobbing stm32f042-0.6.3
[INFO] frobbed toml for stm32f042-0.6.3 written to work/ex/beta-1.38-1/sources/beta-2019-08-13/reg/stm32f042/0.6.3/Cargo.toml
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+1.37.0" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[INFO] running `"/mnt/big/crater/work/local/cargo-home/bin/cargo" "+beta-2019-08-13" "generate-lockfile" "--manifest-path" "Cargo.toml" "-Zno-index-update"`
[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 --target thumbv6m-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