Improve kraken test resiliance

tests/exchange/test_ccxt_compat.py

@@ -224,8 +224,13 @@ class TestCCXTExchange():
         for val in [1, 2, 5, 25, 100]:
             l2 = exchange.fetch_l2_order_book(pair, val)
             if not l2_limit_range or val in l2_limit_range:
-                assert len(l2['asks']) == val
-                assert len(l2['bids']) == val
+                if val > 50:
+                    # Orderbooks are not always this deep.
+                    assert val - 5 < len(l2['asks']) <= val
+                    assert val - 5 < len(l2['bids']) <= val
+                else:
+                    assert len(l2['asks']) == val
+                    assert len(l2['bids']) == val
             else:
                 next_limit = exchange.get_next_limit_in_list(
                     val, l2_limit_range, l2_limit_range_required)