Navigationtree in ZMI is not working.

[sallner]

When attempting to expand a folder with content in the TreeDisplay on the left-hand side of the ZMI, we get the following error under Python 3.

Traceback (most recent call last):
  File "/home/sallner/dev/eggs/waitress-1.0.2-py3.5.egg/waitress/channel.py", line 338, in service
    task.service()
  File "/home/sallner/dev/eggs/waitress-1.0.2-py3.5.egg/waitress/task.py", line 169, in service
    self.execute()
  File "/home/sallner/dev/eggs/waitress-1.0.2-py3.5.egg/waitress/task.py", line 399, in execute
    app_iter = self.channel.server.application(env, start_response)
  File "/home/sallner/zope/Zope/src/ZPublisher/httpexceptions.py", line 33, in __call__
    return self.application(environ, start_response)
  File "/home/sallner/zope/Zope/src/ZPublisher/WSGIPublisher.py", line 248, in publish_module
    response = _publish(request, new_mod_info)
  File "/home/sallner/zope/Zope/src/ZPublisher/WSGIPublisher.py", line 204, in publish
    bind=1)
  File "/home/sallner/zope/Zope/src/ZPublisher/mapply.py", line 85, in mapply
    return debug(object, args, context)
  File "/home/sallner/zope/Zope/src/ZPublisher/WSGIPublisher.py", line 56, in call_object
    return obj(*args)
  File "/home/sallner/zope/Zope/src/Shared/DC/Scripts/Bindings.py", line 323, in __call__
    return self._bindAndExec(args, kw, None)
  File "/home/sallner/zope/Zope/src/Shared/DC/Scripts/Bindings.py", line 360, in _bindAndExec
    return self._exec(bound_data, args, kw)
  File "/home/sallner/zope/Zope/src/App/special_dtml.py", line 203, in _exec
    result = render_blocks(self._v_blocks, ns)
  File "/home/sallner/dev/eggs/DocumentTemplate-3.0a4-py3.5.egg/DocumentTemplate/_DocumentTemplate.py", line 147, in render_blocks
    render_blocks_(blocks, rendered, md)
  File "/home/sallner/dev/eggs/DocumentTemplate-3.0a4-py3.5.egg/DocumentTemplate/_DocumentTemplate.py", line 248, in render_blocks_
    block = block(md)
  File "/home/sallner/dev/eggs/DocumentTemplate-3.0a4-py3.5.egg/TreeDisplay/TreeTag.py", line 115, in render
    return tpRender(v, md, self.section, self.args)
  File "/home/sallner/dev/eggs/DocumentTemplate-3.0a4-py3.5.egg/TreeDisplay/TreeTag.py", line 215, in tpRender
    diff = decode_seq(md['tree-e'])
  File "/home/sallner/dev/eggs/DocumentTemplate-3.0a4-py3.5.egg/TreeDisplay/TreeTag.py", line 667, in decode_seq
    state = decompress(state)
  File "/home/sallner/dev/eggs/DocumentTemplate-3.0a4-py3.5.egg/TreeDisplay/TreeTag.py", line 693, in decompress
    return zlib.decompress(input).decode('utf-8')
zlib.error: Error -3 while decompressing data: incorrect header check

To reproduce:

• Create folder Test
• Inside Test create a folder Subtest
• Reload the ZMI, as the TreeDisplay may not be automatically updated
• Click on the + in front of Test