Perhaps you don't understand the semver very well.
The release is not tied to the release of a specific feature. It's just tied in when you decide to publish a new set of changes and decide what goes in that release.
Everyone measures their own ready chips into the master, and then you test the whole thing and release it.
And the delayed features will go to another release, so 1.9.0-alpha.1 should not be a release of a specific feature
We have version 1.8.0 now, some independent developer releases his feature in the alpha version, we do 1.9.0-alpha.1, then he stalls and solves a bunch of problems.
The release is not tied to the release of a specific feature. It's just tied in when you decide to publish a new set of changes and decide what goes in that release.
Everyone measures their own ready chips into the master, and then you test the whole thing and release it.
And the delayed features will go to another release, so 1.9.0-alpha.1 should not be a release of a specific feature