Linked svg is copied into fodt file


I want to work with LibreOffice and git to let several people edit/update a document.
The document is in fodt format (plain xml text for git) and pictures are all svg (plain xml text for git). Pictures are linked (not embedded) into the document. This setup sounds great for git.

However, svg pictures are actually copied into the fodt file, which is not git-compliant at all as a change in a svg file induces a (large) change into the fodt file.

I tried with png pictures, and they are not copied into the fodt file. So there’s something specific to svg file I don’t really understand. Is this some kind of thumbnail/preview of the svg picture ?

How do I make LibreOffice stop copying linked svg files into the fodt file ?
Tested versions : 6.1 and 6.2

Well, I will use Xelatex as a fallback then… Libreoffice is not git compliant right now.