1.3b2 is Rasterio's second pre-release containing a nearly complete view of new features for 1.3.0. We're not accepting new features for 1.3.0 and are only working on major runtime and installation bugs. If you would be willing to try out this pre-release and provide feedback on GitHub, or in responses to this email, the 1.3.0 release will be better and will arrive sooner.
There's one significant bug fix since 1.3b1: error contexts no longer leak from use of GDAL's coordinate transformer.
Our set of binary wheels is small right now, but we'll keep working on that, and will send updates when we've added support for more platforms.