Code review comment for lp:~barry/ubuntu-system-image/lp1558190

Looks good! I personally prefer adding test descriptions in """ """ for each test case, but that's just my style preference. I suppose checking if the date is higher than the epoch is good enough, but we could think of doing some closer checks to like fetching the local time now and looking if the generated tarball has a higher-or-equal one, to check for any future bugs that might make s-i writing some strange timestamps buuut... that's not really a probable case (can't think of a way that could happen). So a big +1 from me.