Reverting core_signing to the old way.

By reverting django.core.signing to Django 1.11.8 version Django-Q works
This is not designed as a 'good' solution just to show where I think the
problem is.

django_q/core_signing.py

@@ -0,0 +1,76 @@
+from __future__ import unicode_literals
+
+import datetime
+import time
+import zlib
+
+from django.utils import baseconv
+from django.utils.crypto import constant_time_compare
+from django.utils.encoding import force_bytes, force_str, force_text
+from django.core.signing import BadSignature, SignatureExpired, b64_decode, JSONSerializer, \
+    Signer as Sgnr, TimestampSigner as TsS, dumps
+
+dumps = dumps
+
+
+"""
+The loads function is the same as the `django.core.signing.loads` function
+The difference is that `this` loads function calls `TimestampSigner` and `Signer`
+"""
+def loads(s, key=None, salt='django.core.signing', serializer=JSONSerializer, max_age=None):
+    """
+    Reverse of dumps(), raise BadSignature if signature fails.
+
+    The serializer is expected to accept a bytestring.
+    """
+    # TimestampSigner.unsign() returns str but base64 and zlib compression
+    # operate on bytes.
+    base64d = force_bytes(TimestampSigner(key, salt=salt).unsign(s, max_age=max_age))
+    decompress = False
+    if base64d[:1] == b'.':
+        # It's compressed; uncompress it first
+        base64d = base64d[1:]
+        decompress = True
+    data = b64_decode(base64d)
+    if decompress:
+        data = zlib.decompress(data)
+    return serializer().loads(data)
+
+
+class Signer(Sgnr):
+
+    def unsign(self, signed_value):
+        # force_str is removed in Django 2.0
+        signed_value = force_str(signed_value)
+        if self.sep not in signed_value:
+            raise BadSignature('No "%s" found in value' % self.sep)
+        value, sig = signed_value.rsplit(self.sep, 1)
+        if constant_time_compare(sig, self.signature(value)):
+            # force_text is removed in Django 2.0
+            return force_text(value)
+        raise BadSignature('Signature "%s" does not match' % sig)
+
+
+"""
+TimestampSigner is also the same as `django.core.signing.TimestampSigner` but is
+calling `this` Signer.
+"""
+class TimestampSigner(Signer, TsS):
+
+    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)
+        value, timestamp = result.rsplit(self.sep, 1)
+        timestamp = baseconv.base62.decode(timestamp)
+        if max_age is not None:
+            if isinstance(max_age, datetime.timedelta):
+                max_age = max_age.total_seconds()
+            # Check timestamp is not older than max_age
+            age = time.time() - timestamp
+            if age > max_age:
+                raise SignatureExpired(
+                    'Signature age %s > %s seconds' % (age, max_age))
+        return value

django_q/signing.py

@@ -4,7 +4,7 @@ try:
 except ImportError:
     import pickle
 
-from django.core import signing
+from django_q import core_signing as signing
 
 from django_q.conf import Conf