Created attachment 341447 [details]
Minimal example

libxml2 loses the context node after joining nodesets from local and global "//".

The sample program below prints two "bar" nodes for each "doc", but it should print only one. And it prints one "bar" node if I restore the context node (uncomment the line (2)) or simplify the expression on the line (1).

import libxml2

s = """
<x>
  <doc> <foo /> <bar /> </doc>
  <doc> <foo /> <bar /> </doc>
</x>"""
xmldoc = libxml2.parseDoc(s)
baton = xmldoc.xpathNewContext()

res = baton.xpathEval("//doc")
for doc_node in res:
    baton.setContextNode(doc_node)
    res = baton.xpathEval(".//foo | //foo") # (1)
    #baton.setContextNode(doc_node) # (2)
    res2 = baton.xpathEval(".//bar") # (3)
    print res2

baton.xpathFreeContext()
xmldoc.freeDoc()