ShapeUpgrade_UnifySameDomain unif(shape, false, true, false) fails in particular cases

To reproduce :

Draw a sphere
cut it in 2 semi-spheres by a vertical plane
erase one of them
mirror the other to replace the erased one (you'll get a sphere composed by 2 separate semi-spheres)
fuse them (you'll get a new sphere)
use ShapeUpgrade_UnifySameDomain(sphere, false, true, false) to unify the sphere surface

result -- exception (fails creating a gp_Dir(0, 0, 0) or something like this

it don't fail if you skip the erase + mirror part, so it's a problem with the mirrored semisphere.

Max