split: Added error when attempting to create file that already exists as directory

[max-amb]

Fixes #9937

Not sure if error message could be better named

[max-amb]

I am confused why the windows test doesn't work, the code in unix.rs and windows.rs seems the same to me. Can anyone help?

[oech3]

csplit of main's code might help

[max-amb]

csplit does this differently, with

        let file = File::open(file_name)
            .map_err_context(|| format!("cannot open {} for reading", file_name.quote()))?;
        Ok(csplit(&options, &patterns, BufReader::new(file))?)

in csplit.rs, 633-635.
It doesn't differentiate between unix and windows as well.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/timeout/timeout (fails in this run but passes in the 'main' branch)

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/timeout/timeout (passes in this run but fails in the 'main' branch)