ensure we unwrap desc() /label() all the way w/ order by

ensure we unwrap desc() /label() all the way w/ order by

The deprecated logic to move order_by expressions
up into the columns clause needed adjustment to accommodate
for a more deeply-wrapped structure when desc() + label()
 are combined in an order by column.  This structure
now comes from coercions in 1.4.  it's not clear to me
at the moment why it's different from 1.3 but
this shouldn't really matter.

Fixes: #5443
Change-Id: If909a86f715992318d7aa283603197f7711f1d3b