Can't seem to remove "ns0:" namespace declaration [duplicate]

Question

All I'm trying to do is read a local .xml file (encode it UTF-8 so it has the proper header, and re-save the file). However, when I run the following, it adds the dreaded "ns0:" declaration within each XML element:

import xml.etree.ElementTree as ET
import sys, os

# note that this is the *module*'s `register_namespace()` function
# WTF THIS SHOULD WORK....
ET.register_namespace("", "http://www.w3.org/2000/svg")

tree = ET.ElementTree() # instantiate an object of *class* `ElementTree`
tree.parse('//cbweb1/inetpub/x/sitemap/sitemap_index.xml')

tree.write('//cbweb1/inetpub/x/sitemap/test.xml', encoding = 'utf-8', xml_declaration=True)

What am I doing wrong??

FYI, this is Python 2.7.x (have tried with 3.4)

EDIT:

Input:

<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <sitemap>
    <loc>http://www.example.com/something.xml</loc>
    <lastmod>2014-05-01</lastmod>
  </sitemap>
</sitemapindex>

Output:

<?xml version="1.0" encoding="utf-8"?>
<ns0:sitemapindex xmlns:ns0="http://www.sitemaps.org/schemas/sitemap/0.9">
  <ns0:sitemap>
    <ns0:loc>http://www.example.com/something.xml</ns0:loc>
    <ns0:lastmod>2014-05-01</ns0:lastmod>
  </ns0:sitemap>
</ns0:sitemapindex>

Answer 1

If the default namespace in the original input is http://www.sitemaps.org/schemas/sitemap/0.9, as shown in:

<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">

then if you set setting it to something else with

ET.register_namespace("", "http://www.w3.org/2000/svg")

you'll need some other namespace declared in the output for http://www.sitemaps.org/schemas/sitemap/0.9. Instead, you should set it to the same value:

ET.register_namespace("", "http://www.sitemaps.org/schemas/sitemap/0.9")

(Alternatively, you might try simply not setting it to anything at all; perhaps the same namespaces would be used by default in the output that were present in the input.)