Slightly jank fix to deal with extra data after json dict.

Even though the dict decodes just fine, I'm having some cases where
there is additional data after it. The data looks like random junk
bytes.

src/mega/crypto.py

@@ -86,6 +86,8 @@ def decrypt_attr(attr, key):
     attr = aes_cbc_decrypt(attr, a32_to_str(key))
     attr = makestring(attr)
     attr = attr.rstrip('\0')
+    if '"}\0' in attr:
+        attr = attr.split('"}\0')[0] + '"}'
     return json.loads(attr[4:]) if attr[:6] == 'MEGA{"' else False
 
 def a32_to_str(a):