Extra edge of a spherical surface
SetFactory("OpenCASCADE"); Sphere(1)={0,0,0,1,0,Pi/2,Pi/2};
produces one-eighth of a sphere-ball.
The spherical surface 1 (with is mathematically spherical triangle) from the point of view of geometrical module has one extra edge 1 (starting and ending points are 1) and thus the surface 1 is a four-edges and four-vertices quad. This prevent to build transfinite mesh on this surface.
Suitable solution would be to erase correctly this degenerated edge from the surface (curve's loop). This edge has the same start/end point and zero length (and, I suppose, unknown type). It might be done after all geometrical operations and just before meshing. The same kind of edges OCC inserts for rotation operations.
Thank you in advance.