The docs for gst_tag_setter_get_list show G_CONST_RETURN for the returned tag
list, but also say it is to be freed with gst_tag_list_free() after use.  Those
two statements conflict with eachother.  Looking at the code:

  return gst_tag_setter_get_data (setter)->list;

it seems to me that the list shouldn't be freed, but I'm not sure.  In case this
is correct, here's a patch that changes the docs and the prototype to reflect
the situation.