Unable to override default tree delimiter

[thenbe]

The custom delimiter should replace the default delimiter, instead of being appended to it.

Repro: https://observablehq.com/d/96ac483a54482567

Code

data = [
	'foo;bar;http://www.example.com',
	'foo;bar;https://www.example.com/posts/1',
	'foo;baz;https://www.example.com/posts/2',
];

Plot.plot({
	axis: null,
	height: 100,
	margin: 10,
	marginLeft: 40,
	marginRight: 120,
	marks: [Plot.tree(data, { delimiter: ';' })],
});

Expected

In Plot.tree, declaring a custom delimiter ; should result in a tree where only ; is used as a delimiter.

Actual

In Plot.tree, declaring a custom delimiter ; results in a tree where both ; and / are used as delimiters.

[Fil]

Thanks for the report! See #1850 for a potential fix

[mbostock]

Oh, yikes. Good report! Thank you.