better report if the subclass factory has import problems

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@42888 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

wxPython/src/_xrc_ex.py

@@ -10,7 +10,12 @@ TheXmlResource = XmlResource_Get()
 
 
 def _my_import(name):
+    try:
         mod = __import__(name)
+    except ImportError:
+        import traceback
+        print traceback.format_exc()
+        raise
     components = name.split('.')
     for comp in components[1:]:
         mod = getattr(mod, comp)