python之lxml输出原xml中注释问题

原XML中注释如下，经过中间的lxml代码处理后，注释部分跟原xml不一致了，
“<![CDATA[@displayText:ip#@obtainType:1]]>变成了@displayText:ip#@obtainType:1”，没找到解决方法：
原XML：

<![CDATA[@displayText:ip#@obtainType:1]]>

处理代码：
from lxml import etree
tree = etree.parse("test.xml")
fileHandler = open("out1.xml", "wb")
tree.write(fileHandler, encoding="utf-8", xml_declaration=True, pretty_print=True)
fileHandler.close()

处理后输出xml：
<?xml version='1.0' encoding='utf-8'?>

@displayText:ip#@obtainType:1

https://stackoverflow.com/questions/33573807/faithfully-preserve-comments-in-parsed-xml-python-2-7