Am 08.03.2018 um 09:56 schrieb ParticlePeter:

I am publishing a v1.x.y library (master branch) and would like to increment it to v2.0.0. I still would like to add bug fixes to the v1.x.y variant.

My preferred workflow would be to fork master into branch v1 and use master branch for v2.

Now, if I would tweak branch v1 and add a semVer tag, would it still be published in the registry?

Yes, that works. Branches and tags are generally handled more or less
independent of each other (except when working with a locally checked
out branch).