For Android having 2021a1 and 2021b would be inconvenient. Because 
there are hardcoded places which expect that tzdata version is exactly
5 characters. And we can't update that code along with time zone files. 

Most feasible way we see is to release it as "2021a Android revision 1",
but that revision field is not exposed by any APIs. There will be
inconsistencies between different APIs on "What tzdb release are you using".

Personally I agree with Tom. Releasing 2021b as 2021a + Samoa changes
is less disruptive.


On Wed, 22 Sept 2021 at 19:31, Paul Eggert via tz <tz@iana.org> wrote:
In light of the previous discussions and the fact that we need a new
release very soon, I propose the following:

* We release 2021b pretty much as-is (with the usual release
administrivia such as updating NEWS).

* We also generate a separate 2021a1 version, which is like 2021a except
with the Samoa change that is prompting 2021b. This version recognizes
the concerns about the number of changes to pre-1970 timestamps in
2021b. I'll do this by publishing a patch to 2021a, along with a patched
tarball, on my website at UCLA.

Although this is effectively a fork in the short term, the idea is that
it's a small fork with the intent that we'll work together to combine
the two approaches in later releases, taking the abovementioned concerns
into account.

There is precedent for this approach, in that when there were
compatibility problems with earlier releases, I generated alternate
tarballs to support downstream users while they were adapting their
database readers. Although the two cases are not the same, generating an
alternate distribution also has the benefit of giving us time.

Although I haven't had time to read all the discussions so far (and
email is still rolling in), I will try to take these discussions into
account when writing the NEWS entries for the two versions.

After the versions are published and the dust has settled, I hope that
we can incorporate some of the suggestions that have been made, as we
will then have time to implement and test them. I don't want this
followup discussion to take a looong time, though, as the goal is to
combine the two approaches soon.

Since Samoa's rules change in less than 72 hours I plan to generate
these new versions soon.