Fix missing diff header lines when diffing a file that has only property
changes.

* subversion/libsvn_client/diff.c
  (diff_content_changed): If the text diff was empty, assume no header was
    printed (unless we printed one explicitly).


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1619476 13f79535-47bb-0310-9956-ffa450edef68
Raise a tree-conflict and continue the update, rather than stopping,
with an obstruction, when an incoming server-excluded node conflicts
with a locally added node.

* subversion/libsvn_wc/update_editor.c
  (absent_node): Raise a tree-conflict.

* subversion/tests/cmdline/authz_tests.py
  (authz_tree_conflict): Expect a tree-conflict and a complete update.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1619495 13f79535-47bb-0310-9956-ffa450edef68