ST_DistanceSphere allows operations on mixed SRIDs

[Mike Taves]

With PostGIS 1.5, using ST_Distance_Sphere with mixed SRIDs raised an error:

SELECT ST_Distance_Sphere(ST_SetSRID(p1, 4326), p2) AS q1,
  ST_Distance_Sphere(p1, ST_SetSRID(p2, 4326)) AS q2,
  ST_Distance_Sphere(ST_SetSRID(p1, 4269), ST_SetSRID(p2, 4326)) AS q3
FROM (
    SELECT ST_MakePoint(0, 0) AS p1, ST_MakePoint(0, 1) AS p2
) f;
ERROR:  geometry_distance_spheroid: Operation on two GEOMETRIES with different SRIDs

But with recent versions of PostGIS, these queries are permitted without error or notice.

[pramsey]

See also #2642

[pramsey]

Fixed at r13826