Changing style of existing text to "preformat" leaves the <br/> tags

[GoogleCodeExporter]

What steps will reproduce the problem?
1. Open a new document
2. Type 3 lines of text
3. Select all and change style to "preformat"
4. Everything looks fine until you close the document and reopen it.  Now the 
lines appear double spaced.  If you view the source you'll see the <pre> block 
contains <br/> tags.

What is the expected output? What do you see instead?
<br/> tags need to be removed (converted to newlines really).  Perhaps other 
tags are left in as well?

What version of the product are you using? On what operating system?
0.5.1 on xubuntu 12.04.

Please provide any additional information below.

Original issue reported on code.google.com by cru...@gmail.com on 3 Jun 2012 at 7:24