I don't suppose you could tell us where the version number comes from then? I looked at opt/keybase/version of the 'now' package (20170214-1250 UTC) you host for Linux x64 and it says v1.4.12. What is the git commit reference for that version?
Is there another location for official source releases? The Nix expression [1] builds from source from GitHub releases, but it could easily be modified to point to an different address on the web to stay more up-to-date.