BUG guess_Datetime_format doesn't guess 27.03.2003 14:55:00.000

[MarcoGorelli]

----> 1 guess_datetime_format('27.03.2003 14:55:00.000')

File ~/pandas-dev/pandas/_libs/tslibs/parsing.pyx:967, in pandas._libs.tslibs.parsing.guess_datetime_format()
    965 print('tokens[i]', tokens[i])
    966 print('padding', padding)
--> 967 token_filled = _fill_token(tokens[i], padding)
    968 if token_format is None and token_filled == parsed_formatted:
    969     format_guess[i] = attr_format

File ~/pandas-dev/pandas/_libs/tslibs/parsing.pyx:1026, in pandas._libs.tslibs.parsing._fill_token()
   1024 print('token', token)
   1025 seconds, nanoseconds = token.split(".")
-> 1026 seconds = f"{int(seconds):02d}"
   1027 # right-pad so we get nanoseconds, then only take
   1028 # first 6 digits (microseconds) as stdlib datetime

ValueError: invalid literal for int() with base 10: ''

It should return None, or guess the format, but not error