Add note about legacy metadata format

freqtrade/constants.py

@@ -36,7 +36,6 @@ AVAILABLE_DATAHANDLERS = ['json', 'jsongz', 'hdf5']
 BACKTEST_BREAKDOWNS = ['day', 'week', 'month']
 BACKTEST_CACHE_AGE = ['none', 'day', 'week', 'month']
 BACKTEST_CACHE_DEFAULT = 'day'
-BACKTEST_CACHE_NONE = 'none'
 DRY_RUN_WALLET = 1000
 DATETIME_PRINT_FORMAT = '%Y-%m-%d %H:%M:%S'
 MATH_CLOSE_PREC = 1e-14  # Precision used for float comparisons

freqtrade/data/btanalysis.py

@@ -191,6 +191,9 @@ def find_existing_backtest_stats(dirname: Union[Path, str], run_ids: Dict[str, s
                 try:
                     backtest_date = strategy_metadata['backtest_start_time']
                 except KeyError:
+                    # TODO: this can be removed starting from feb 2022
+                    # The metadata-file without start_time was only available in develop
+                    # and was never included in an official release.
                     # Older metadata format without backtest time, too old to consider.
                     return results
                 backtest_date = datetime.fromtimestamp(backtest_date, tz=timezone.utc)