NBSP Chars Escaped Incorrectly for XML Documents

[Jordan Harrison]

Explanation

I am no xml expert so forgive me if I am wrong but I believe NBSP characters should be escaped as   in xml documents because   is not defined in xml. There are a small number of named entities defined in xml but nbsp is not one of them according to the docs here https://www.w3.org/TR/xml11/#sec-predefined-ent

Problem

nbsp chars are encoded as   for xml documents

How should it behave?

If the document is an xml document then nbsp chars should be encoded as  

[Andrea Giammarchi]

fixed and landed