xml-stylesheet and all processing instructions deleted.

Steps to reproduce:

Is this a new preferred behaviour?

• open Inkscape
• open a svg file with a element such as
• "?xml-stylesheet type='text/css' href='/CSS/my.css'?"
• ..at the top of file, before svg element.
• Save the file as Inkscape svg (default)

What happened?

• When opened by a text file editor the xml-stylesheet element has been deleted.
• All such https://www.w3.org/TR/xml-stylesheet/ elements have been deleted.
• All processing instructions have been deleted. http://www.xmlplease.com/xml/pi/

What should have happened?

• Please leave them alone.

Inkscape Version and Operating System:

• Inkscape Version: 1.0beta1 (fe3e3069, 2019-09-17) ...
• Operating System: ... Win10
• Operating System version: ... Recent, up2date.