New Markdown editor replaces certain characters with HTML-safe entities

The Markup/Markdown text of an issue-description placed in Bitbucket's built-in issue tracker (including this very one, that’s used for Bitbucket’s site itself) will load back for editing in a corrupted form if text contains characters such as greater-thans, less-thans, ampersands, single quotes, or double quotes. Submitting without making any changes in the text-box (for instance, just changing the issue-title) actually causes changes in the description because the reverse conversions do not occur, and the entity-codes are taken as literals. This causes further corruption on later edits because the new ‘&’s are then converted into &}}which is then (on next edit) converted to {{&, etc.

Browsers used:

• Firefox 60.6.1esr
• Chrome 73.0.3683.103
• Firefox 67.0 (Quantum)
• Chrome 64.0.3282.167

Operating systems used:

• Windows 7 Enterprise
• Windows 10 Enterprise

To reproduce:

1. Using one of the above browsers, create a new issue using Bitbucket’s internal issue-tracker.
2. Into the description, paste the contents of the attached markdown file.
3. Save the issue.
4. Return to the issue you just created and select “Edit”.
5. Note that occurrences of the above-listed characters will appear in the editor itself as their HTML-entity representations e.g. '.
6. (optional) Saving the document will result in these entities being saved literally, even if the user took no actions to change the description, but instead changed the issue-status, title, or other.