pango_layout_set_attributes changed semantics at some point
Calling pango_layout_set_attributes
with the same PangoAttrList
as the layout currently has at present does nothing.
It used to update the layout with any updates to the attribute list.
At a guess this change happened with 1bb4e61c.
If such updating is meant to not be allowed then I suggest that the documentation for pango_layout_set_attributes
be updated to state that the layout takes ownership of the attribute list (but not the ref) and that therefore the caller should not change the list.