[treereader] Do not warn about file change if *this is new:
[treereader] Do not warn about file change if *this is new:

The reader cannot know who read that tree before, maybe another reader,
and warning about previous state right after birth is too much of a guess.
Fixes an issue where RDF creates exactly that situation.

olifre/root,karies/root,root-mirror/root,karies/root,karies/root,olifre/root,root-mirror/root,root-mirror/root,karies/root,olifre/root,karies/root,karies/root,karies/root,olifre/root,olifre/root,root-mirror/root,olifre/root,karies/root,olifre/root,root-mirror/root,olifre/root,olifre/root,root-mirror/root,karies/root,karies/root,olifre/root,root-mirror/root,root-mirror/root,olifre/root,root-mirror/root,root-mirror/root,karies/root,root-mirror/root