Can't save blank text lines

When using the V3 template to edit label lines for category content, it ignores attempts to save empty lines, instead reverting them to whatever they previously contained.

Reproduction steps:

1. Do a fresh V3 template install
2. Edit the content for the Rules tab
3. Populate one of the included empty text lines in the example
4. Close, save, and reopen the text editor
5. Erase the content of the previously edited line
6. Close, save, and, reopen the text editor

Expected result: Empty line committed

Actual result: Line reverts to previous contents

Found a workaround: Create a new line and don't touch its contents, just move it into the desired ordering position.