5.5-RC3 - Code Editor Broken (change of behavior; Inserts br in content)

[Justin_K]

While testing out my plugins against 5.5, there has been a breaking change in the post editor: while in CODE EDITOR mode (note: not visual editor) mode, the instant the mouse focus is taken out of the content box, it appends <br /> tags at the end of every line. This is expected with the visual editor, but not with the code editor. The regression breaks the functionality of my plugin.

Here's a short video showing the behavior: ​https://lnk2.tk/snaps/2020-08-11_11.31.07.mp4

[Justin_K]

Addendum: it's also doing the opposite - it's removing br tags that I've explicitly entered in the content, apparently making it impossible to use the code editor to write code.

[Justin_K]

After some more digging through the multiple duplicate versions of autop, this bug is caused by the js functions removep and & autop in wp-includes/js/dist/autop.js. If I return at the first line of those functions, the code editor behaves properly.

[noisysocks]

Duplicate of #2833.