fixed SchemaPath initialization bug in MetabaseBase.add_schema(), for megatests
fixed SchemaPath initialization bug in MetabaseBase.add_schema(), for megatests

cjlee112/pygr,ctb/pygr,ctb/pygr,theoryno3/pygr,RitwikGupta/pygr,ctb/pygr,RitwikGupta/pygr,cjlee112/pygr,theoryno3/pygr,ctb/pygr,RitwikGupta/pygr,theoryno3/pygr,GenDataPro/pygr,cjlee112/pygr,cjlee112/pygr,ctb/pygr,GenDataPro/pygr,GenDataPro/pygr