Ignore MissingSection exception in _uninstall_part().

slapos/rebootstrap/__init__.py

@@ -93,7 +93,10 @@ Buildout will be restarted automatically to have this change applied.
 _uninstall_part_orig = zc.buildout.buildout.Buildout._uninstall_part
 def _uninstall_part(self, part, installed_part_options):
   _uninstall_part_orig(self, part, installed_part_options)
-  location = self[part].get('location')
+  try:
+    location = self[part].get('location')
+  except zc.buildout.buildout.MissingSection:
+    return
   if location and sys.executable.startswith(location):
     message = """
 ************ REBOOTSTRAP: IMPORTANT NOTICE ************