Update tests

freqtrade/data/history.py

@@ -241,9 +241,9 @@ def _load_cached_data_for_updating(pair: str, timeframe: str, timerange: Optiona
     if not data.empty:
         if start and start < data.iloc[0]['date']:
             # Earlier data than existing data requested, redownload all
-            return DataFrame(columns=DEFAULT_DATAFRAME_COLUMNS), None
-
-        start = data.iloc[-1]['date']
+            data = DataFrame(columns=DEFAULT_DATAFRAME_COLUMNS)
+        else:
+            start = data.iloc[-1]['date']
 
     start_ms = int(start.timestamp() * 1000) if start else None
     return data, start_ms