Steps to reproduce:
- Start with a page that contains ==Sections==
- Mark it up for translation properly, i.e., in a way that minimizes the amount of hassle the translators will have with wikitext. This means that you are marking all the section headings like this: == <translate> Sections </translate> ==
- Mark the page for translation. This will change == <translate> Sections </translate> == into this:
- Click the 'Edit source' link next to any of the section headings that were individually tagged for translation.
- Read the error message.
By splitting the content into three lines, the section heading is non-existent as far as the edit section button is concerned. It's possible that not screwing with the formatting so much, i.e., putting == <translate> <!--T:1--> Sections </translate> == all on one line, would be a sufficient solution.