fails:Time#strftime rounds an offset to the nearest second when formatting with %z
fails:Time#strftime with %N formats the picoseconds of the second with %12N
fails:Time#strftime supports RFC 3339 UTC for unknown offset local time, -0000, as %-z
fails:Time#strftime applies '-' flag to UTC time
fails:Time#strftime ignores '-' flag for non-UTC time
fails:Time#strftime works correctly with width, _ and 0 flags, and :
