test: apply microsecond precision to test framework logging

This makes it easier to compare test and bitcoind logs -
combine_logs.py orders by timestamp and will be more precise.

test/functional/test_framework/test_framework.py

@@ -7,6 +7,7 @@
 import configparser
 from enum import Enum
 import argparse
+from datetime import datetime, timezone
 import logging
 import os
 import platform
@@ -837,9 +838,16 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
         # User can provide log level as a number or string (eg DEBUG). loglevel was caught as a string, so try to convert it to an int
         ll = int(self.options.loglevel) if self.options.loglevel.isdigit() else self.options.loglevel.upper()
         ch.setLevel(ll)
+
         # Format logs the same as bitcoind's debug.log with microprecision (so log files can be concatenated and sorted)
-        formatter = logging.Formatter(fmt='%(asctime)s.%(msecs)03d000Z %(name)s (%(levelname)s): %(message)s', datefmt='%Y-%m-%dT%H:%M:%S')
-        formatter.converter = time.gmtime
+        class MicrosecondFormatter(logging.Formatter):
+            def formatTime(self, record, _=None):
+                dt = datetime.fromtimestamp(record.created, timezone.utc)
+                return dt.strftime('%Y-%m-%dT%H:%M:%S.%f')
+
+        formatter = MicrosecondFormatter(
+            fmt='%(asctime)sZ %(name)s (%(levelname)s): %(message)s',
+        )
         fh.setFormatter(formatter)
         ch.setFormatter(formatter)
         # add the handlers to the logger