Mismatch in water-lines-casing SQL

[pnorman]

The SQL for water-lines-casing is

(SELECT 
    way,waterway,
    CASE WHEN tunnel IN ('yes','culvert') THEN 'yes' ELSE 'no' END AS int_tunnel 
  FROM planet_osm_line
  WHERE waterway IN ('stream','drain','ditch')
    AND (tunnel IS NULL OR tunnel != 'yes')
) AS water_lines_casing

The tunnel condition in the WHERE selects waterways without a tunnel=yes tag, but the case condition targets tunnel=yes. The only time int_tunnel is yes is for tunnel=culvert.