#4014 Extended Copy <br> tags scrambled by Story previews

[Alexandre Leroux]

Using latest slash.

When there are <br><br> tags in a story's Extended Copy box, after a few previews, new <br> tags are inadvertently added to the text.

It's easy to reproduce. In a new story, add to the extended copy:
test2<br> <br>
test2<br> <br>
test2<br> <br>
test

And after hitting a few times "preview story" you'll end up with something like:
test2<br> <br>&nbsp; <br>test2<br> <br>&nbsp; <br>test2<br> <br>&nbsp; <br>test2<br>
&nbsp; <br>&nbsp; <br>

Introducing several new and unwanted <br> tags.

Thanks