Removed "is not None"

https://stackoverflow.com/users/566644/lauritz-v-thaulow

freqtrade\configuration\configuration.py:461 reduced checks

freqtrade\persistence\trade_model.py:fee_updated - reduced code

tests/plugins/test_pairlist.py

@@ -1169,7 +1169,7 @@ def test_pricefilter_desc(mocker, whitelist_conf, markets, pairlistconfig,
                           )
     whitelist_conf['pairlists'] = [pairlistconfig]
 
-    if desc_expected is not None:
+    if desc_expected:
         freqtrade = get_patched_freqtradebot(mocker, whitelist_conf)
         short_desc = str(freqtrade.pairlists.short_desc())
         assert short_desc == desc_expected