Comment 0 for bug 1557260

With the sig V4 effort in https://review.openstack.org/#/c/211933/, we're finding a few issues with current boto. And from their README [1], it sounds like the likelihood of getting them fixed in the 2.x series is diminished:

> Boto3, the next version of Boto, is now stable and recommended for general use. It can be used side-by-side with Boto in the same project, so it is easy to start using Boto3 in your existing projects as well as new projects. Going forward, API updates and all new feature work will be focused on Boto3.
>
> To assist users who still depend on Boto and cannot immediately switch over, we will be triaging and addressing critical issues and PRs in Boto in the short term. As more users make the switch to Boto3, we expect to reduce our maintenance involvement over time. If we decide on a cutoff date or any significant changes to our maintenance plan, we will make pre-announcements well ahead of schedule to allow ample time for our users to adapt/migrate.

I'm not entirely sure whether sig V4 issues would be covered by "critical issues" or not, but getting on 3.x sooner rather than later is probably a good idea.