[xml] A rare bug?

["David Zhuo" <dzhuo1 gmail com>]

hi All,
I have a schema and a XML file and used xmllint to verify that the XML is in fact confirm to the schema. The rare problem I am running into is that different version of xmllint will have very different behavior and I am not certain which version is at fault. Here is an example:

$ /usr/bin/xmllint --version
/usr/bin/xmllint: using libxml version 20620
   compiled with: DTDValid FTP HTTP HTML C14N Catalog XPath XPointer XInclude Iconv Unicode Regexps Automata Schemas Modules
$ /usr/bin/xmllint --noout --schema http://www.youtube.com/xsd/metadata_0.2.xsd /tmp/test.xml 
/tmp/test.xml validates

a new version 20623, however, fails:

$ /usr/bin/xmllint --version
/usr/bin/xmllint: using libxml version 20623
  
compiled with: Threads Tree Output Push Reader Patterns Writer SAXv1
FTP HTTP DTDValid HTML Legacy C14N Catalog XPath XPointer XInclude
Iconv ISO8859X Unicode Regexps Automata Expr Schemas Schematron Modules
Debug 
$ /usr/bin/xmllint --noout --schema http://www.youtube.com/xsd/metadata_0.2.xsd /tmp/test.xml 
/tmp/test.xml:18: element keywords: Schemas validity error : Element '{
http://search.yahoo.com/mrss}keywords': [facet 'pattern'] The value 'London,Sci Fi,Aliens' is not accepted by the pattern '(.*,){2,}.*'.
/tmp/test.xml:18: element keywords: Schemas validity error : Element '{
http://search.yahoo.com/mrss}keywords': 'London,Sci Fi,Aliens' is not a valid value of the local atomic type.
/tmp/test.xml fails to validate

the test is performed with the same XML and schema and the only different is the version of xmllint used. Build version 20620 successfully validate the XML while version 20623 does not. 

the sample XML is attached. can someone tell me if this is a bug or not?

thx!
david

Attachment: test.xml
Description: Text Data