add Date field to Release file

[AtnNn]

We've been using freight to manage the RethinkDB apt repo, but it seems to be incompatible with the newest version of apt. This simple patch seems to fix the issue.

Originally reported here rethinkdb/rethinkdb#5174:

With the new release of apt-1.1, the apt repositories at http://download.rethinkdb.com/apt/ are failing to update..

$ apt update
...
W: Failed to fetch http://download.rethinkdb.com/apt/dists/stretch/Release  Invalid 'Date' entry in Release file /var/lib/apt/lists/partial/download.rethinkdb.com_apt_dists_stretch_Release
E: Some index files failed to download. They have been ignored, or old ones used instead.

[mmoll]

@rcrowley any opinion on that? As Debian/stretch and Ubuntu/xenial use apt 1.1.x now, this is starting to hit more and more people...

[stahnma]

Does having date in there just end up as noop for older versions of apt?

[AtnNn]

@stahnma I believe so. There's a Date field here: http://ftp.ca.debian.org/debian/dists/oldoldstable/Release

[mattock]

We're also experiencing this exact issue. I can test the proposed fix if that helps get a fixed release out.

We've also received reports of similar, but different issue, which I reported here: #66.

[mattock]

As already mentioned in issue #70, there's a maintained fork of freight here. We've just made the first release (0.3.6).

[danielmewes]

It looks like this is fixed in the new repository https://github.com/freight-team/freight/blob/master/lib/freight/apt.sh#L176 . Should this be closed?