Philip and I have started implementing op_depth in the NODES table, but we soon found there is more to do than simply calculating a value here and there.
("Implementing op_depth" means enabling multiply nested copies/replacements/adds/deletes etc., with the ability to revert at each level.) In the meantime, some tests were breaking, so we have made the full op_depth support conditional on SVN_WC__OP_DEPTH. Why? The interim 0/1/2 op_depth values have been working OK in the limited context of the amount of nesting that BASE+WORKING supports. We might want to make a transition from BASE_NODE/WORKING_NODE to NODES first, before enabling the full op_depth support. That is probably the main reason why this further conditional is useful. The alternative would be to complete op_depth support before switching the default build over to NODES. Any concerns about working within SVN_WC__OP_DEPTH? - Julian