Generate out-of-date errors for paths which already exist (rather than waiting for an error when we try to write over existing content).
Generate out-of-date errors for paths which already exist (rather than
waiting for an error when we try to write over existing content).

* subversion/libsvn_fs/editor.c:
  (can_create): new helper function
  (add_directory_cb, add_file_cb, add_symlink_cb, copy_cb, move_cb):
    call the new can_create() helper


git-svn-id: f8a4e5e023278da1e04e203c7fe051e3c4285d88@1339892 13f79535-47bb-0310-9956-ffa450edef68

YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion,YueLinHo/Subversion