Re: fix intermittent test failure triggered by split /tmp usage

[Jim Meyering]

On Tue, Jul 18, 2023 at 11:14 AM Pádraig Brady <P@draigbrady.com> wrote:
> The new test where `split -n 1/2 /dev/zero` exhausts /tmp
> will trigger other false positive failures in the test suite
> which happens often when running tests with RUN_VERY_EXPENSIVE_TESTS set.
>
> The attached patches tackle this by consolidating temp file handling
> for tac and split, so that have a configurable $TMPDIR.
>
> We then use $TMPDIR in an adjusted test to point to
> a mounted file system to provide better isolation.

Nice work. That all looks fine. Thanks!
The only nit I saw was the use of $(pwd), when $PWD works fine.
Sure, existing uses of $(pwd) outnumber $PWD 25 to 10, but those
25 should probably change, too.