see sparklemotion/nokogiri#2947
output:
using libxml2 version 21200-GITv2.11.0-70-gd38e73f9
vanilla.html:
htmlReadFile encoding: UTF-8
htmlReadMemory encoding: UTF-8
bad-charset.html:
htmlReadFile encoding: UTF-8
htmlReadMemory encoding: UTF-8
using libxml2 version 21200-GITv2.11.0-71-gec7be506
vanilla.html:
htmlReadFile encoding: UTF-8
htmlReadMemory encoding: (null)
bad-charset.html:
htmlReadFile encoding: XXXXX
htmlReadMemory encoding: XXXXX