That will most likely be the parasites at apple leaching of libxml2, they are a trillion dollar company and libxml2 is currently without a maintainer. Makes me extremely angry. They are linking various of their system frameworks against libxml2 these days and they use incompatible versions, causing endless headaches. It's a real shame libxml2 uses an MIT license instead of the GPL3. I'll look into sometime when I have a moment.
EDIT:
https://github.com/kovidgoyal/calibr...a0bbe2305056f7 I was wrong its libexpat not libxml2 in this case