File "/home/replaceafill/.buildout/eggs/zope.publisher-3.12.6-py2.7.egg/zope/publisher/publish.py", line 137, in publish
  publication.afterCall(request, obj)
File "/home/replaceafill/.buildout/eggs/zope.app.publication-3.14.0-py2.7.egg/zope/app/publication/browser.py", line 46, in afterCall
  super(BrowserPublication, self).afterCall(request, ob)
File "/home/replaceafill/.buildout/eggs/zope.app.publication-3.14.0-py2.7.egg/zope/app/publication/zopepublication.py", line 213, in afterCall
  txn.commit()
File "/home/replaceafill/.buildout/eggs/transaction-1.1.1-py2.7.egg/transaction/_transaction.py", line 329, in commit
  self._commitResources()
File "/home/replaceafill/.buildout/eggs/transaction-1.1.1-py2.7.egg/transaction/_transaction.py", line 441, in _commitResources
  rm.tpc_begin(self)
File "/home/replaceafill/.buildout/eggs/ZODB3-3.10.5-py2.7-linux-x86_64.egg/ZODB/Connection.py", line 551, in tpc_begin
  self._normal_storage.tpc_begin(transaction)
File "/home/replaceafill/.buildout/eggs/ZODB3-3.10.5-py2.7-linux-x86_64.egg/ZODB/BaseStorage.py", line 224, in tpc_begin
  raise POSException.ReadOnlyError()