Bounded vertex selection not guaranteed to work on meshes with randomly flipped face normals

[MightyBOBcnc]

If a mesh has randomly flipped face normals like in the above image (with some facing inward and some facing outward) then bounded vertex selection between two separated vertices (non-adjacent) will not always succeed. Sometimes it does and sometimes it does not, depending on the normal orientation of the faces linked to the active vertex.

This is due to the complexity of the bmesh loop cycle design and the fact that loops cannot be visualized in the 3D viewport which makes it extremely difficult to develop against.

The offending code is in the partial_loop_vert_manifold function.