What is wrong with:

print $query->header(-charset=>'utf-8');
print $query->start_html(-encoding=>'utf-8');
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It outputs this:

Content-Type: text/html; charset=utf-8
 
<?xml version="1.0" encoding="utf-8"?>
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It sets the charset in the HTTP header, and the encoding on the XML. It does not add any meta http-equiv tag with the Content-Type, but that is not needed since the Content-Type is set in the header.

What browser is not setting the encoding from the Content-Type?