[tz] Bulletin C 51: No leap second in June 2016, but new leap second file

[Paul Eggert]

In http://mm.icann.org/pipermail/tz/2016-January/023057.html Brian 
Inglis wrote:

> https://hpiers.obspm.fr/iers/bul/bulc/ntp/leap-seconds.list
> The comment says 28 December 2016 but the expiry timestamp 3684182400
> is actually 2016-09-30 00:00:00+0000

Ouch! That's definitely a bug in the leap-seconds.list file. I will BCC: 
this message to the webmaster for that web page.

A less-important issue: that web page has a Last-Modified time (reported 
via the HTTP header) of 2016-01-11 11:06:36 UTC, even though the web 
page's contents give a last update equal to 3661459200 NTP, i.e., 
2016-01-11 00:00:00 UTC. I guess they have just one-day resolution for 
theirannouncements' time stamps, but hey! they're time nerds! The two 
time stamps should be identical.

> so they must be fairly confident
> that current predictions of dUT1 remaining low until year end will be
> borne out, and Bulletin C 52 will announce no change in July. 

If the actual expiry is 2016-09-30 they're giving themselves the 
opportunity to decide in July to insert a leap second at the end of 
September, which is conservative: although the protocols allow leap 
seconds to be inserted in September, it has never happened and is 
unlikely to happen this year.