Fix seek offset deltas

We always store the offset of the next available message, so we shouldn't decrement the offset deltas
when seeking by an extra 1

kafka/consumer.py

@@ -280,12 +280,6 @@ class SimpleConsumer(Consumer):
                     reqs.append(OffsetRequest(self.topic, partition, -2, 1))
                 elif whence == 2:
                     reqs.append(OffsetRequest(self.topic, partition, -1, 1))
-
-                    # The API returns back the next available offset
-                    # For eg: if the current offset is 18, the API will return
-                    # back 19. So, if we have to seek 5 points before, we will
-                    # end up going back to 14, instead of 13. Adjust this
-                    deltas[partition] -= 1
                 else:
                     pass