Impossible to undo Convert to Blocks when post_content contains a core oEmbed link

[chrisvanpatten]

Describe the bug
Clicking "Convert to Blocks" successfully converts classic editor content to blocks, and appears to add to the undo history, but clicking "undo" has no result.

In my testing this is caused by oEmbed lines in post_content pointing to WP posts.

To Reproduce
Steps to reproduce the behavior:

1. Create a post in the Classic Editor with a WordPress oEmbed link, e.g.…

My paragraph

https://www.chrisvanpatten.com/notes-from-wordcamp-halifax-2018

My other paragraph

2. Open the post in Gutenberg
3. Open the Classic Editor block's settings menu and select "Convert to Blocks"
4. Note that the Undo button is enabled
5. Try to click undo
6. See nothing happen

Expected behavior
Either this process should be "undoable" or the undo button shouldn't change its state.

Screenshots

Desktop (please complete the following information):

• OS: macOS High Sierra 10.13.5
• Browser: Safari 11.1.1
• Gutenberg Version: 3.0.1

[mcsf]

Related: #6325 (comment)

[mcsf]

@chrisvanpatten, thanks for the report.

I can't repro. Do you have content I can use to test this?

[chrisvanpatten]

@mcsf I did a bit more testing and I've narrowed it down. The client has WordPress oEmbed links in their post_content, e.g.

My paragraph

https://www.website.com/2018/08/internal-link/

My other paragraph

If I remove those oEmbed lines from the post_content, conversion and undo work fine. With the oEmbeds, you can convert to blocks but not back the other way.

[mcsf]

That makes much more sense, thanks for checking!

[mcsf]

Closing in favor of umbrella issue #8119