tests: use basic format code "%Y" instead of "%s" for test portability On Windows, strftime() doesn't support format code "%s", and it causes "invalid format string" error. https://msdn.microsoft.com/en-us/library/fe06s4ak.aspx test-command-template.t examines not seconds value in UTC, but arithmetic calculation. Therefore, using format code "%Y" instead of "%s" should be reasonable. FYI: - Python standard library reference doesn't list "%s" up in format code list required for "C standard (1989 version)", even though it also mentions that additional format codes are required for "C standard (1999 version)" https://docs.python.org/2.7/library/datetime.html#strftime-and-strptime-behavior - The Open Group Base Specifications Issue 7 (IEEE Std 1003.1-2008, 2016 Edition) doesn't require strftime to support format code "%s" http://pubs.opengroup.org/onlinepubs/9699919799/functions/strftime.html - "man strftime" of (Open/Oracle) Solaris and Mac OS X (= UNIX certified OSs) describes about format code "%s"