bug#56025: 29.0.50; em-extpipe-test-2 times out on EMBA and Cygwin

[Ken Brown]

On 6/18/2022 3:02 PM, Jim Porter wrote:
> On 6/18/2022 10:52 AM, Ken Brown wrote:
> > No, I'm seeing the same results on Emacs 28.  On both Emacs 28 and Emacs 29, 
> > rev is apparently not seeing EOF unless echo outputs a newline, so rev keeps 
> > waiting for input.
>
> Ah ha! Thanks for debugging this. The minimal fix then would be to change the 
> command in em-extpipe-test-2 to either of these:
>
>    echo -N "bar" | rev *>temp

This doesn't work.  It still hangs when run interactively, as does the 
equivalent

     echo -N bar | sh -c "rev >temp"

>    *echo "bar" | rev *>temp

This works interactively, but I don't know the appropriate syntax for modifying 
the test.  Naively replacing each 'echo' by '*echo' caused the 'should-parse' to 
fail.
> One last[1] question: if you ran "echo -n bar | rev" in Cygwin Bash, does it 
> hang there too?

No.

> Maybe this is just a Cygwin limitation, or maybe Eshell is doing 
> something wrong with its built-in pipelines in this situation.

My guess is that it's the latter, but I don't know if it's worth pursuing this 
if Cygwin and EMBA are the only platforms on which there's a problem.  Of 
course, there might be other platforms and no one has reported it.

Once the test is fixed to succeed on Cygwin, we should probably revert the 
change that caused the extpipe tests to be skipped on EMBA, just to make sure 
that the same fix works there.

Ken