I am stitching together XML files using the lxml.etree library and namespaces are being dropped on write.

Input.xml

<?xml version="1.0" encoding="UTF-8"?>
<haul>
    <uuid>abc</uuid>
    <port xmlns="hello"
          xmlns:a="hello">
        <v>
            <a:value>0</a:value>
            <type>int</type>
        </v>
    </port>
</haul>

I tried this code:

test.py

tree = load_tree_from_file('Input.xml')
port = tree.find('{hello}port')
v = port.find('{hello}v')
v2=copy.deepcopy(v)
port.append(v2)

d = os.path.dirname(__file__)
tree.write(os.path.join(d, 'Output.xml'))

I got this output:

Output.xml

<haul>
    <uuid>abc</uuid>
    <port xmlns="hello" xmlns:a="hello">
        <v>
            <a:value>0</a:value>
            <type>int</type>
        </v>
        <v>
            <value>0</value>
            <type>int</type>
        </v>
    </port>
</haul>

I expected–and need–the <value> Element to be <a:value> like the first one.