editor crashes while using indent feature

[Prateeksha]

This is zim 0.65
Platform: posix
Locale: en_IN ISO8859-1
FS encoding: UTF-8
Python: (2, 7, 12, 'final', 0)
Gtk: (2, 24, 30)
Pygtk: (2, 24, 0)
Zim revision is:
  branch: zim-trunk
  revision: 805 <email address hidden>
  date: 2015-11-01 15:42:45 +0100

======= Traceback =======
  File "/usr/lib/python2.7/dist-packages/zim/gui/__init__.py", line 885, in _action_handler
    method(*arg)
  File "/usr/lib/python2.7/dist-packages/zim/gui/pageview.py", line 5543, in undo
    self.undostack.undo()
  File "/usr/lib/python2.7/dist-packages/zim/gui/pageview.py", line 4641, in undo
    self._replay(self.stack[i].reversed())
  File "/usr/lib/python2.7/dist-packages/zim/gui/pageview.py", line 4677, in _replay
    self.buffer.insert_parsetree_at_cursor(data)
  File "/usr/lib/python2.7/dist-packages/zim/gui/pageview.py", line 780, in insert_parsetree_at_cursor
    self._insert_element_children(root, raw=raw)
  File "/usr/lib/python2.7/dist-packages/zim/gui/pageview.py", line 870, in _insert_element_children
    set_indent(int(element.attrib['indent']))
  File "/usr/lib/python2.7/dist-packages/zim/gui/pageview.py", line 847, in set_indent
    assert len(tags) <= 1, 'BUG: overlapping indent tags'
AssertionError: BUG: overlapping indent tags