This seems to have been added to /etc/X11/Xsession.d/30xorg-common_xresources but that file contains a bug:
on lines 16 and 23 $(XRDBOPTS) should actually be ${XRDBOPTS}
This seems to have been added to /etc/X11/ Xsession. d/30xorg- common_ xresources
but that file contains a bug:
on lines 16 and 23 $(XRDBOPTS) should actually be ${XRDBOPTS}