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

[Joel E. Denny via llvm-commits]

jdenny-ornl wrote:

@uweigand Thanks!  That was the clue I needed.

I found there are four tests that have a similar pattern and cause trouble on my local system:

- fork-sigusr.test: Seemed to hang, but I never saw it kill the shell that was running check-fuzzer.  That appears to be a different result than @uweigand saw, so maybe there's something non-deterministic, or maybe our shells are different.
- merge-sigusr.test: Killed the shell.
- sigint.test: Seemed to hang.
- sigusr.test: Killed the shell.

If I disable those tests, check-fuzzer behaves as at the parent commit.

I have a simple lit fix I've pushed to this branch.  It also makes check-fuzzer behave as at the parent commit.

I'm hesitant to land the new version as last time was a bit of a disaster.  Based on @uweigand's comments,  some bots are still recovering.  Sorry!  Who knows what other trouble might be lurking on the next attempt.

Any advice on how to proceed?

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