Tree conflict resolution options on command-line

Hi,

Using: svn 1.8.8 (r1568071)

When attempting to merge a change into my working copy, I am getting a tree
conflict (change adds a file, file already exists). No problem with the
conflict.

    Conflict discovered when trying to add 'foo\A\B\c.p'.
    An object of the same name already exists.
    Select: (mf) my version, (tf) their version, (p) postpone,
            (q) quit resolution, (h) help:

If I select to use either of 'mf' or 'tf', I get:

    Summary of conflits:
      Tree conflicts: 0 remainings (and 1 already resolved)
    svn: E155027: Tree conflict can only be resolved to 'working' state;
    'foo\A\B\c.p' not resolved.

My question is: If a tree conflict can only ever be resolved to 'working',
then
 (a) why isn't 'working' an option in the resolution prompt?; and
 (b) why am I being asked to choose something that isn't applicable anyway?

---
Daniel Becroft