Dirty fix for error '_object_has_no_attribute_'getSlave' in EtherCAT extension

traceback:
File "/home/developer/WorkData/PLC/beremiz/beremiz/IDEFrame.py", line 1433, in OnPouSelectedChanged
window.RefreshView()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 837, in RefreshView
self.RefreshProcessVariables()
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/ConfigEditor.py", line 886, in RefreshProcessVariables
slaves = self.Controler.GetSlaves(**self.CurrentNodesFilter)
File "/home/developer/WorkData/PLC/beremiz/beremiz/etherlab/EthercatMaster.py", line 341, in GetSlaves
for slave in self.Config.getConfig().getSlave():
<type 'exceptions.AttributeError'>:_'lxml.etree._Element'_object_has_no_attribute_'getSlave'

Steps to reproduce problem:

- Add new EtherCAT master
- Add new EthercatNode to the master
- double click on


this is looks like dirty hack to fix strange problem with initial[0]
changing its type after returning from _init_ method to lxml.etree._Element
As a result all methods generated by class factory are lost.

For example, in function initMethod initial[0].__class__ points to
xmlclass.xmlclass.Config. After map(self.append, initial)
self.Config.__class__ is 'xmlclass.xmlclass.Config' as well.
But after returning from initMethod (_init) in CreateElement
self.Config.__class__ has changed to lxml.etree._Element.


I've noticed similar behavior if copy/deepcopy is used for any child
of etree.ElementBase. See simple example below.
[-------------------------------------------------------------]
#!/usr/bin/python

from __future__ import print_function
from lxml import etree
import copy

class DefaultElementClass(etree.ElementBase):
def getLocalTag(self):
return etree.QName(self.tag).localname


def printInformation(x):
print(x, x.__class__, "getLocalTag" in dir(x))


a = DefaultElementClass()
printInformation(a)

#
printInformation(copy.copy(a))
printInformation(copy.deepcopy(a))
[-------------------------------------------------------------]

#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# See COPYING.Runtime file for copyrights details.
#

from __future__ import absolute_import
from ctypes import CDLL, RTLD_GLOBAL, pointer, c_int, POINTER, c_char, create_string_buffer


def TryPreloadXenomai():
    """
    Xenomai 3 (at least for version <= 3.0.6) do not handle properly dlclose
    of shared objects whose dlopen did trigger xenomai_init.
    As a workaround, this pre-loads xenomai libraries that need to be
    initialized and call xenomai_init once for all.

    Xenomai auto init of libs MUST be disabled (see --auto-init-solib in xeno-config)
    """
    try:
        for name in ["cobalt", "modechk", "copperplate", "alchemy"]:
            globals()[name] = CDLL("lib"+name+".so", mode=RTLD_GLOBAL)
        cobalt.xenomai_init(pointer(c_int(0)), pointer((POINTER(c_char)*2)(create_string_buffer("prog_name"), None)))
    except Exception:
        pass