assertion failed when source text contains \r character

[zombiepigdragon]

MRE:

// cosmic-text = "0.7.0"
use cosmic_text::{Attrs, Buffer, FontSystem, Metrics};

fn main() {
    let font_system = FontSystem::new();
    let metrics = Metrics::new(14, 20);
    let mut buffer = Buffer::new(&font_system, metrics);
    buffer.set_size(80, 25);
    let attrs = Attrs::new();
    let message = "A\rB"; // Problem!
    buffer.set_text(message, attrs);
}

Discovered while trying to develop an X11 application- the Enter key sent a "\r" instead of a "\n", which my prototype application (not using Editor) simply appended to the end of the rendered buffer, causing a crash when the next character was appended.

The cause seems to be that \r is treated as a paragraph separator by unicode-bidi, but not by the lines iterator from std uses to do paragraph separator in buffer.set_text(), so when the paragraph is sent to be shaped it's split into two paragraphs and triggers the assert.