(epub-test-fail: pub-xml-non-validating_invalid)

[gautierchomel]

The pub-xml-non-validating_invalid test fails at

This SPINE does not look invalid to me

<manifest>
 <item id="content_001" href="content_001.xhtml" media-type="application/xhtml+xml" />
 <item id="content_002" href="content_002.xhtml" media-type="application/xhtml+xml" />
 <item id="nav" properties="nav" href="nav.xhtml" media-type="application/xhtml+xml" />
</manifest>
<spine>
<!--  
<itemref idref="content_001" />
 -->
<itemref idref="content_001" />
<itemref idref="content_002" />
 </spine>

I tryed to modify as follow :

  <spine>
<itemref idref="content001" />
<itemref idref="content002" />
 </spine>

Thorium refuses to open the file.