HAMMER_BTREE_TYPE_NONE
elm->base.btype != HAMMER_BTREE_TYPE_NONE);
elm->base.btype == HAMMER_BTREE_TYPE_NONE);
case HAMMER_BTREE_TYPE_NONE:
elm->base.btype = HAMMER_BTREE_TYPE_NONE;
case HAMMER_BTREE_TYPE_NONE:
hmp->root_btree_beg.btype = HAMMER_BTREE_TYPE_NONE;
hmp->root_btree_end.btype = HAMMER_BTREE_TYPE_NONE;