If 2D-curves are requested in intersection result but they cannot be created (by some reason) then the full set of curves (3D and two 2D) is rejected from the intersection result.
1. New testgrid "lowalgos/intss" has been created. It will contain all test cases on geometrical intersection of two surfaces ("intersect" DRAW-command) and two faces ("bopcurves" DRAW-command).
2. New test case for the issue #28493 has been created because the problem is not reproduced on MASTER.
3. Test case (lowalgos/intss/bug24472) for the issue #29501 has been modified in order to check loops of the resulting intersection curves.