Travis CI issues with tagged releases

[Dids]

Tagged releases break conditional support for Travis's stage system, which means that the tagged releases aren't getting pushed to nuget.org or to GitHub Releases.

More information here:
travis-ci/beta-features#40

[Dids]

From what I can tell, a tagged release simply breaks conditionals entirely, so we might just have to drop using conditionals for now, and see if we can just use bash/shell expressions to validate if it's the correct branch and a tagged release or not.

[Dids]

This just keeps getting better.

For some reason Travis itself has no idea what branch of tag it's using:

Skipping a deployment with the script provider because this branch is not permitted: v1.0.0-beta8
Skipping a deployment with the script provider because this is not a tagged commit

[Dids]

Looks like we might just need to account for the following:

The documentation now reflects that TRAVIS_BRANCH is set to the tag name when the build was initiated by a tag.

However, it seems also reasonable to me that TRAVIS_BRANCH should be empty for tag builds. I do wonder if this change would break existing builds, however.

Source:
travis-ci/travis-ci#4745 (comment)