docxtpl generates broken docx if some core_properties was changed

[av-gantimurov]

Describe the bug

docxtpl generates broken docx if some core_properties was changed before save.
If open in Microsoft Office Word 2010-2019 - error occures.
it is not error in python-docx - with it works and generates normal documents.

it works fine with docxtpl version 0.11.5, but in 0.12.0 and newer generated document is broken.

To Reproduce

installing python-docx and creating empty test document

python -m pip install python-docx

from docx import Document
doc = Document()
doc.core_properties.keywords = "keywords; works; fine"
doc.save("empty.docx")

empty.docx is opened fine and without fails or errors in Microsoft Office Word.

success

Installing properly working docxtpl 0.11.5

python -m pip install docxtpl==0.11.5

from docxtpl import DocxTemplate
tpl = DocxTemplate("empty.docx")
tpl.render({})
tpl.docx.core_properties.keywords = "keywords; still; works"
tpl.save("success.docx")

error

Bug occures in docxtpl from 0.12 to 0.16.4 and current development.

python -m pip install docxtpl

from docxtpl import DocxTemplate
tpl = DocxTemplate("empty.docx")
tpl.render({})
tpl.docx.core_properties.keywords = "keywords; still; works"
tpl.save("error.docx")

Problem occured if open in Microsoft Office Word 2010-2019.
When open error.docx in Microsoft Office Word you see error message.
When i try to show extra properties tab in file properties I don't see keywords were set.
In libreoffice error.docx is opened without fails. Exiftools shows properly set keywords.

i compared empty.docx, success.docx and error.docx.
they difference only in docProps/core.xml file.

Here i attach difference with beautified xml

1. empty.docx

<cp:coreProperties
	xmlns:cp="http://schemas.openxmlformats.org/package/2006/metadata/core-properties"
	xmlns:dc="http://purl.org/dc/elements/1.1/"
	xmlns:dcterms="http://purl.org/dc/terms/"
	xmlns:dcmitype="http://purl.org/dc/dcmitype/"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<dc:title/>
	<dc:subject/>
	<dc:creator>python-docx</dc:creator>
	<cp:keywords>success; fine</cp:keywords>
	<dc:description>generated by python-docx</dc:description>
	<cp:lastModifiedBy/>
	<cp:revision>1</cp:revision>
	<dcterms:created xsi:type="dcterms:W3CDTF">2013-12-23T23:15:00Z</dcterms:created>
	<dcterms:modified xsi:type="dcterms:W3CDTF">2013-12-23T23:15:00Z</dcterms:modified>
	<cp:category/>
</cp:coreProperties>

2. success.docx

<cp:coreProperties
	xmlns:cp="http://schemas.openxmlformats.org/package/2006/metadata/core-properties"
	xmlns:dc="http://purl.org/dc/elements/1.1/"
	xmlns:dcterms="http://purl.org/dc/terms/"
	xmlns:dcmitype="http://purl.org/dc/dcmitype/"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<dc:title/>
	<dc:subject/>
	<dc:creator>python-docx</dc:creator>
	<cp:keywords>error</cp:keywords>
	<dc:description>generated by python-docx</dc:description>
	<cp:lastModifiedBy/>
	<cp:revision>1</cp:revision>
	<dcterms:created xsi:type="dcterms:W3CDTF">2013-12-23T23:15:00Z</dcterms:created>
	<dcterms:modified xsi:type="dcterms:W3CDTF">2013-12-23T23:15:00Z</dcterms:modified>
	<cp:category/>
</cp:coreProperties>

3. error.docx

<cp:coreProperties
	xmlns:cp="http://schemas.openxmlformats.org/package/2006/metadata/core-properties"
	xmlns:dc="http://purl.org/dc/elements/1.1/"
	xmlns:dcterms="http://purl.org/dc/terms/"
	xmlns:dcmitype="http://purl.org/dc/dcmitype/"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
	<dc:title/>
	<dc:subject/>
	<dc:creator>python-docx</dc:creator>
	<cp:keywords>success; fine</cp:keywords>
	<dc:description>generated by python-docx</dc:description>
	<cp:lastModifiedBy/>
	<cp:revision>1</cp:revision>
	<dcterms:created xsi:type="dcterms:W3CDTF">2013-12-23T23:15:00Z</dcterms:created>
	<dcterms:modified xsi:type="dcterms:W3CDTF">2013-12-23T23:15:00Z</dcterms:modified>
	<cp:category/>
	<cp:keywords
		xmlns:cp="http://schemas.openxmlformats.org/officeDocument/2006/custom-properties">error
	</cp:keywords>
</cp:coreProperties>

As you can see in error.docx <cp:keywords> dublicated and has additional xmlns:cp="http://schemas.openxmlformats.org/officeDocument/2006/custom-properties

Expected behavior

Script above must create docx document without consistency errors.

Screenshots

Error in Microsoft Office 2010

Additional context

Python 3.10

[abhishekjain12]

Same issue. Is there any fix?

2 custom properties make a difference:

• lastModifiedBy
• revision

if I remove these, then it works fine

Both properties has xmlns:cp="http://schemas.openxmlformats.org/officeDocument/2006/custom-properties"

python-openxml/python-docx#1037