Wp-calypso: Custom HTML Block: Copy/Paste from one block into another only selects entire contents

[smithkyle45]

Steps to reproduce

1. Starting at URL: https://wordpress.com/home/
2. Create or edit any page or post (to enter the editor)
3. Add two Custom HTML blocks, input some HTML into both
4. Try to copy a piece of the HTML from either block
5. Paste the HTML into one of the Custom HTML blocks

What I expected

I was expecting to be able to paste one line of HTML from one block into another.

What happened instead

It appears to select the entire contents of the Custom HTML block, wrapped by the following:

<!-- wp:html --><!-- /wp:html --> 

Browser / OS version

Chrome 83.0.4103.61
macOS Catalina 10.15.5

Screenshot / Video

Screen recording: https://d.pr/v/bWhFsd/fM8zTS45X4

Context / Source

A user reported this to me in live chat. They normally write poems/prose with custom HTML blocks and noted that they were able to copy/paste in this style up until a few weeks ago.

user-report in 14727191-hc.

[zdenys]

I noticed the same thing when I was troubleshooting a user case. The block should indeed only copy the selected part of the text, not the entire content of the block.

[zdenys]

Just noting that it happens for the Shortcode Block as well https://github.com/Automattic/wp-calypso/issues/43264

[simison]

This might be fixed in Gutenberg 8.3 with https://github.com/WordPress/gutenberg/pull/22793

[razvanpapadopol]

I can confirm this has been fixed in Gutenberg 8.3 so now should be fixed on wpcom.
Here's a demo where I was copying a single line, the whole block and then two lines of HTML: https://cloudup.com/cZtadhxgwnvmmmm