CKeditor adds HTML tags with no content

[routinet]

CKEditor 3.2.1 (revision 5372)

When starting CKEditor with no content, switching to source view shows "<br />". If I remove the text, switch to HTML view and back to source view again, the additional "<br />" reappears.

This same behavior occurs if the only content is matched by the protectedSource regex. For example, this following content:

<? $stuff='stuff'; ?>

will result in this output:

<? $stuff='stuff'; ?><br />

The following examples will not:

stuff<? $stuff='stuff'; ?>

or

<? $stuff='stuff'; ?>some html