Migration-only function

async def storPropSet(self, buid, prop, valu):
        '''
        Migration-only function
        '''
        assert self.buidcache.disabled

        indx = prop.type.indx(valu)
        if indx is not None and len(indx) > MAX_INDEX_LEN:
            mesg = 'index bytes are too large'
            raise s_exc.BadIndxValu(mesg=mesg, prop=prop, valu=valu)

        univ = prop.utf8name[0] in (46, 35) # leading . or #
        bpkey = buid + prop.utf8name

        self._storPropSetCommon(buid, prop.utf8name, bpkey, prop.pref, univ, valu, indx)