symfony/symfony — pull request #2952 by mpdude (2011-12-23 18:10:23+00:00)
Title: Be more tolerant and also accept <esi:include ...></esi:include>

I know this is not 100% standards compliant, but:

We need to to some XHTML processing on the output using PHP's DOM extension and the underlying libxml2.

libxml2 seems to be unable to keep the tag as such and will expand it to .

Note this has nothing to do with having LIBXML_NOEMPTYTAG set (http://php.net/manual/de/domdocument.savexml.php). Rather it seems to be a problem for libxml that it cannot recognize as an "EMPTY" tag (in the DTD sense) because it is not defined in a standard xhtml1-strict DTD.