[xml] Error on including and importing schemas already parsed

[Oblivian <oblivian users sourceforge net>]

In looking for an answer some problems I've had importing and including schema in the same namespace I ran across these two messages and have not found any additional information.  I think the issue I ran into and the ones in the below links are caused by the same code.  Basically xmlschemas.c should allow imports/includes and redefinitions from the same schemaLocation.  I've attached a test case and the proposed patch to fix.

http://mail.gnome.org/archives/xml/2007-January/msg00042.html
http://mail.gnome.org/archives/xml/2007-January/msg00077.html

Since the svn code is the same as shown in msg00077 and I have found no further discourse on the subject, I'm assuming this was never addressed, but it would be useful for more complex schemas.

Attachment: test-cases.tar.bz2
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Attachment: libxml2-svn-20090302-fix-validation-import-include.patch
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