HTML mode: Adding new lines within <td> tags generates extra, unwanted <td> tags

Expected behavior

When creating tables, I would like any content that I add within a tag to remain within that tag so that it looks like the content is in one table cell after saving. I'd expect to be able to add content to a table cell that includes multiple paragraphs or line breaks.

Actual behavior

If I add line breaks to content within one tag/table cell, then extra, unwanted tags are generated.

Steps to reproduce the behavior

1. Navigate to the editor for a post and switch to the HTML view.
2. Copy/paste the following HTML code to create a table:

<table>
<tbody>
<tr>
<td>AB</td>
<td></td>
</tr>
</tbody>
</table>

3. Now add some line breaks between A and B:

<table>
<tbody>
<tr>
<td>A

B</td>
<td></td>
</tr>
</tbody>
</table>

4. Save your changes then view the HTML again. You'll see that extra tags are added:

<table>
<tbody>
<tr>
<td>A</td>
<td>B</td>
<td></td>
</tr>
</tbody>
</table>

Tested on iPad Mini, iOS 11.3, Aztec 9.6.1

Reported in 272318-h.

Start in the HTML view and reproduce the table example from the issue on iOS, then inspect the save-and-reload path used by the Aztec editor. Done means line breaks between A and B remain inside one element and the saved HTML no longer creates extra cells.