handle empty keys which apparently happen in v2 torrents

ui/medashare/btv/bencode.py

@@ -70,11 +70,11 @@ def decode_list(x, f):
 
 def decode_dict(x, f):
     r, f = {}, f+1
-    lastkey = ''
+    lastkey = None
     while x[f] != b'e'[0]:
         k, f = decode_string(x, f)
         k = k.decode('us-ascii')
-        if lastkey >= k:
+        if lastkey is not None and lastkey >= k:
             raise ValueError
         lastkey = k
         r[k], f = decode_func[x[f]](x, f)
@@ -339,9 +339,13 @@ class _TestCases(unittest.TestCase):
 	def test_bencode(self):
 		test_bencode()
 
+		self.assertEqual(bencode({'': 5}), b'd0:i5ee')
+
 	def test_bdecode(self):
 		test_bdecode()
 
+		self.assertEqual(bdecode(b'd0:i5ee'), { '': 5 })
+
 try: #pragma: no cover
     import psyco
     psyco.bind(bdecode)