Patch taken from the Debian package for python-axolotl-0.1.39.
See <https://bugs.gnu.org/29415>.

Description: Removes IV paramenter from AES constructor, since it is not necessary for ctr mode.
Author: Josue Ortega <josue@debian.org>
Last-Update: 2017-04-13

--- a/axolotl/sessioncipher.py
+++ b/axolotl/sessioncipher.py
@@ -228,13 +228,7 @@
         # counterint = struct.unpack(">L", counterbytes)[0]
         # counterint = int.from_bytes(counterbytes, byteorder='big')
         ctr = Counter.new(128, initial_value=counter)
-
-        # cipher = AES.new(key, AES.MODE_CTR, counter=ctr)
-        ivBytes = bytearray(16)
-        ByteUtil.intToByteArray(ivBytes, 0, counter)
-
-        cipher = AES.new(key, AES.MODE_CTR, IV=bytes(ivBytes), counter=ctr)
-
+        cipher = AES.new(key, AES.MODE_CTR, counter=ctr)
         return cipher