[DRE-maint] Bug#1119023: ruby-nokogiri ftbfs and autopkg test fails with libxml2 2.15.x

[Matthias Klose]

Package: src:ruby-nokogiri
Version: 1.18.10+dfsg-1
Severity: serious
Tags: sid forky ftbfs

one ruby-nokogiri autopkg test fails with libxml2 2.15.x, same is seen 
during the build.

[...]
  28s Finished in 4.024093s, 682.6384 runs/s, 2442.0412 assertions/s.
  28s
  28s   1) Failure:
  28s 
Nokogiri::SAX::TestCase::Nokogiri::XML::SAX::Parser::.parse_file#test_0002_parses 
a compressed file [test/xml/sax/test_parser.rb:84]:
  28s Expected nil to not be nil.
  28s
[...]

that one may be related (from the NEWS file):

The parser option XML_PARSE_UNZIP is now required to read compressed data.