Couchbase Server 4.6 GA will be released very soon, but that will be just the Enterprise Edition (EE). There will be a 4.6 Community Edition, but that comes usually 6 months or more later. You can read more here.
This strategy with EE/CE is the way Couchbase (the company) releases software, and it lets us fund development of Couchbase Server. Another alternative to get this bug fix: some users will cherry pick patches and build their own Couchbase Server but that’s most appropriate if you know what you’re doing. Hope that helps.