Wiki editor removes code blocks contents

Summary

• Switching from rich text to source in Wiki editor removes code blocks contents.
• Clicking "Save changes" from rich text Wiki editor removes code blocks contents.

Steps to reproduce

Switching

1. Create/edit a Wiki page with source code blocks
2. Switch to rich text editor
3. Switch back to source

Saving

1. Create/edit a Wiki page with source code blocks
2. Switch to rich text editor
3. Click "Save changes"

What is the current bug behavior?

All code blocks are empty.

What is the expected correct behavior?

Code blocks should not be made empty.

Output of checks

This bug happens on GitLab.com (both "Current" and "Next")