Vulnerability in libxml2 allows denial of service
If entities expansion in the XML parser is asked for,
it is possble to craft relatively small input document leading
to excessive on-the-fly content generation.
This patch accounts for those replacement and stop parsing
after a given threshold. it can be bypassed as usual with the
HUGE parser option.
(from redmine: issue id 1726, created on 2013-03-26, closed on 2013-04-11)