Convert two tests to work with both Python 2 and 3

Now these two tests work without having to use 2to3

Examples/test-suite/python/python_destructor_exception_runme.py

@@ -1,7 +1,11 @@
 import python_destructor_exception
-from StringIO import StringIO
 import sys
 
+if sys.version_info[0:2] < (3, 0):
+    import StringIO as io
+else:
+    import io
+
 def error_function():
     python_destructor_exception.ClassWithThrowingDestructor().GetBlah()
 
@@ -9,13 +13,13 @@ def runtest():
     attributeErrorOccurred = False
     try:
         error_function()
-    except AttributeError, e:
+    except AttributeError:
         attributeErrorOccurred = True
     return attributeErrorOccurred
 
 def test1():
     stderr_saved = sys.stderr
-    buffer = StringIO()
+    buffer = io.StringIO()
     attributeErrorOccurred = False
     try:
         # Suppress stderr while making this call to suppress the output shown by PyErr_WriteUnraisable