+diff -Naur VTK-4.2.6-original/Wrapping/Python/vtk/__helper.py VTK-4.2.6-patched/Wrapping/Python/vtk/__helper.py
+--- VTK-4.2.6-original/Wrapping/Python/vtk/__helper.py 2001-10-31 23:30:50.000000000 +0300
++++ VTK-4.2.6-patched/Wrapping/Python/vtk/__helper.py 2007-01-15 12:23:15.631470353 +0300
+@@ -9,7 +9,8 @@
+ """ Checks to see if the ImportError was because the library
+ itself was not there or because there was a link error. If there
+ was a link error it raises a LinkError if not it does nothing."""
+- del sys.modules['vtk.%s'%mod_name]
++ if sys.modules.has_key('vtk.%s'%mod_name):
++ del sys.modules['vtk.%s'%mod_name]
+ mod = 'vtk' + string.upper(mod_name[0]) + mod_name[1:] +'Python'
+ if string.find(str(exc), mod) == -1:
+ raise LinkError, str(exc)