Fix python3 only code

.travis.yml

@@ -5,13 +5,19 @@ services:
   - mongodb
 
 python:
+  - "2.7"
   - "3.6"
 
 env:
     - DJANGO=2.0
     - DJANGO=1.11.9
     - DJANGO=1.8.18
 
+matrix:
+  exclude:
+    - python: "2.7"
+      env: DJANGO=2.0
+
 sudo: false
 
 addons:

django_q/core_signing.py

@@ -62,7 +62,7 @@ def unsign(self, value, max_age=None):
         Retrieve original value and check it wasn't signed more
         than max_age seconds ago.
         """
-        result = super().unsign(value)
+        result = super(TimestampSigner, self).unsign(value)
         value, timestamp = result.rsplit(self.sep, 1)
         timestamp = baseconv.base62.decode(timestamp)
         if max_age is not None:

django_q/queues.py

@@ -1,6 +1,7 @@
 """
 The code is derived from https://github.com/althonos/pronto/commit/3384010dfb4fc7c66a219f59276adef3288a886b
 """
+import sys
 
 import multiprocessing
 import multiprocessing.queues
@@ -48,7 +49,11 @@ class Queue(multiprocessing.queues.Queue):
     """
 
     def __init__(self, *args, **kwargs):
-        super(Queue, self).__init__(*args, ctx=multiprocessing.get_context(), **kwargs)
+        if sys.version_info < (3, 0):
+            super(Queue, self).__init__(*args, **kwargs)
+        else:
+            super(Queue, self).__init__(*args, ctx=multiprocessing.get_context(), **kwargs)
+
         self.size = SharedCounter(0)
 
     def put(self, *args, **kwargs):