test_rdiffBackupStat2RSS: drop broken Option.__setitem__

this code referenced non existing variables, it was not used

slapos/test/test_rdiffBackupStat2RSS.py

@@ -9,8 +9,7 @@ from slapos.resilient.rdiffBackupStat2RSS import genRSS
 class Option(dict):
   def __init__(self, **kw):
     self.__dict__.update(kw)
-    def __setitem__(i, y):
-        self.__dict__[i] = y
+
 
 class TestRdiffBackupStat2RSS(unittest.TestCase):
   def setUp(self):