fixed bug in SerialMesh::stitching_helper related to incorrect boundary IDs when two surfaces within the same mesh.
fixed bug in SerialMesh::stitching_helper related to incorrect boundary IDs when two surfaces within the same mesh.

Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh,Mbewu/libmesh