[Inkscape-devel] undo crash

Mental,

I had to revert document-undo.cpp to 1.21 because your version crashes on any attempt to undo with:

** ERROR **: file xml/simple-session.cpp: line 45 (virtual Inkscape::XML::Event* Inkscape::XML::SimpleSession::commitUndoable()): assertion failed: (_in_transaction) aborting...

Sorry I didn't discover this yesterday, was too busy with other things. But please do be more careful with testing before committing.