Beautifier adds unexpected text when used on xml file #627

I use prettydiff as a beautifier as part of atom-beautifier. I recently encountered an odd behavior and was able to boil it down to the following minimal example:

This xml

<module name="foo" ver="1.0">
  <encodingRules null=" "/>
<type name="Header" len="3"></type>

is "beautified" to

<module name="foo" ver="1.0">
  <encodingRules null=" "/>
<type name=" Header" len=" 3"="3""></type>

Problem: The values now have a leading space-char and len got an extra ="3"" .
As soon as null=" " is removed, the beautifier works.

Since this did not happen with some other beautifiers I thought it might be worth a mention.