We still want to package a prerelease VSIX as a GitHub release artifact and (if possible) publish it to the Open VSX Registry. Until the VSCE Marketplace fully supports semver, we can skip publishing to it when a prerelease tag is present and display a warning instead.
The VS Code Marketplace doesn't support publishing versions with prerelease tags - see https://github.com/microsoft/vsmarketplace/issues/50 and https://code.visualstudio.com/api/working-with-extensions/publishing-extension#prerelease-extensions
We still want to package a prerelease VSIX as a GitHub release artifact and (if possible) publish it to the Open VSX Registry. Until the VSCE Marketplace fully supports semver, we can skip publishing to it when a prerelease tag is present and display a warning instead.