[llvm] [lit] Echo full RUN lines in case of external shells (PR #65267)

[Joel E. Denny via llvm-commits]

jdenny-ornl wrote:

Thanks for the info, and sorry for all the trouble.  I am now able to reproduce on a local system: `ninja check-fuzzer` kills my terminal window with signal 12.  I'll keep poking at it as I have time.  If you see any additional clues, please post them here.

https://github.com/llvm/llvm-project/pull/65267