When a merge involves an incoming change that is to be applied to a node that
doesn'e exist in the WC, the non-existent node is the tree conflict victim.
Presently metadata is stored about it in the parent directory's WC entry. It
would be much simpler w.r.t. "walking" the WC and various other internal tasks,
if every tree conflict victim had an "entry".
Thus, we should probably make each victim, including enversioned/non-existent
ones, have an "entry".
As a follow-on, perhaps the tree conflict metadata itself could then be stored
in the victim's entry rather than in the parent dir's entry. That should
simplify a lot of code too, especially with regard to several APIs and internal
functions presently needing the adm_access of the target's parent.