Add initial regression test playing with depth expansion during update/move
handling. This somehow caused a segfault.

The scenarios that I intended to test here looks a lot like the cases that
would needed to be handled for mixed revision moves, but I didn't get that
far.

* subversion/libsvn_wc/wc_db_update_move.c
  (mark_tree_conflict): Add assertion right before the segfault.

* subversion/tests/libsvn_wc/op-depth-test.c
  (finite_move_update_bump): Update caller.
  (move_depth_expand): New function.
  (test_list): Add move_depth_expand as XFail.

* subversion/tests/libsvn_wc/utils.c
  (sbox_wc_update_depth): Add argument (equivalent to --set-depth)
  (sbox_wc_update): Update caller. Pass depth unknown, like 'svn' does.

* subversion/tests/libsvn_wc/utils.h
  (sbox_wc_update_depth): Add argument.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1455881 13f79535-47bb-0310-9956-ffa450edef68