ST_ChangeEdgeGeom does not check if edge exists

[robe]

I can do this:

 SELECT topology.ST_ChangeEdgeGeom('ma_topo', 4,  ST_GeomFromText('LINESTRING(228591.10 893900.4,228622.6 893844.3,228641.6 893816.6,
 228704.5 893778.5)', 26986) );

Even though I have no edge 4. and the function happily reports:

Edge 4 changed

Also why do we break out checking x and y? instead of using a spatial check?

[strk]

Fixed in r7227