Comment 2 for bug 282941

The change I'm doing does end up doing redundant work. Namely it computes the delta 2 times. The first time to figure out what to apply to the tree, and the second time to determine how to update the dirstate. So it should be changed to compute the delta, cache it, and then pass it to the WT.update_basis_by_delta().
So I'm going to leave this bug open for the short term.

Note also bugs like bug #780677 which make pull slower than it needs to be.