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"
tests: add test-commit-interactive-curses.t "require tic" for test portability
Standard library of Python on Windows doesn't have curses module.