test: Ignore UTF-8 errors in assert_debug_log

read() fails in text mode when the unicode hasn't been fully written
yet. Fixes: "wallet_importdescriptors.py: can't decode bytes in position
228861-228863: unexpected end of data"
(bitcoin/bitcoin#28030)

Author: MarcoFalke

test/functional/test_framework/test_node.py

@@ -440,7 +440,7 @@ def assert_debug_log(self, expected_msgs, unexpected_msgs=None, timeout=2):
 
         while True:
             found = True
-            with open(self.debug_log_path, encoding='utf-8') as dl:
+            with open(self.debug_log_path, encoding="utf-8", errors="replace") as dl:
                 dl.seek(prev_size)
                 log = dl.read()
             print_log = " - " + "\n - ".join(log.splitlines())