fixed xmlHasNsProp() bugs for defaulted from DTD attribs, added a specific

* tree.c python/tests/Makefile.am python/tests/attribs.py:
  fixed xmlHasNsProp() bugs for defaulted from DTD attribs,
  added a specific regression test
* python/generator.py: xmlHasNsProp() and xmlHasProp() shall
  not raise exceptions when failing to find the attribute.
Daniel
diff --git a/python/tests/Makefile.am b/python/tests/Makefile.am
index b8ee7b7..9a326e4 100644
--- a/python/tests/Makefile.am
+++ b/python/tests/Makefile.am
@@ -2,6 +2,7 @@
 
 PYTESTS=	\
     build.py	\
+    attribs.py	\
     tst.py	\
     tstxpath.py	\
     xpathext.py	\