[lxml-dev] fix for another memory leak

[Narayan Desai]

In addition to the memory leak in the Element.get method, I have
recently been seeing memory leaks in Element.Attrib.has_key. This
results in the following trace from valgrind:
==12133== 8 bytes in 4 blocks are definitely lost in loss record 2 of 48
==12133==    at 0x401B422: malloc (vg_replace_malloc.c:149)
==12133==    by 0x453D8B5: xmlStrndup (in /usr/lib/libxml2.so.2.6.23)
==12133==    by 0x453D943: xmlStrdup (in /usr/lib/libxml2.so.2.6.23)
==12133==    by 0x453E0D1: xmlStrcat (in /usr/lib/libxml2.so.2.6.23)
==12133==    by 0x44E98A1: xmlNodeListGetString (in /usr/lib/libxml2.so.2.6.23)
==12133==    by 0x44EF6D2: xmlGetNoNsProp (in /usr/lib/libxml2.so.2.6.23)
==12133==    by 0x4462ED0: __pyx_f_5etree_7_Attrib_has_key (etree.c:5389)
==12133==    by 0x80B6BE3: (within /usr/bin/python2.3)
==12133==    by 0x80B8356: PyEval_EvalCodeEx (in /usr/bin/python2.3)
==12133==    by 0x80B85D4: PyEval_EvalCode (in /usr/bin/python2.3)
==12133==    by 0x80D8EFF: PyRun_InteractiveOneFlags (in /usr/bin/python2.3)
==12133==    by 0x80D9018: PyRun_InteractiveLoopFlags (in /usr/bin/python2.3)

The following patch appears to fix things for me. It is basically
copied from the Element.get fix.
 -nld

Index: src/lxml/etree.pyx
===================================================================
--- src/lxml/etree.pyx  (revision 23162)
+++ src/lxml/etree.pyx  (working copy)
@@ -855,6 +855,7 @@
             result = tree.xmlGetNoNsProp(self._c_node, tag)
         else:
             result = tree.xmlGetNsProp(self._c_node, tag, ns)
+        tree.xmlFree(result)
         return result is not NULL
 
     def __contains__(self, key):