There doesn't seem to be a stable/3.0.x branch for mdsal, like there is for odlparent.
Yeah, mdsal has not branched yet for Sodium, so Neon stuff is still on master. This is a normal state of affairs for MRI -- we do not branch next development until we need to.
Wouldn't it be better to track matching tags (i.e. v3.0.6 for mdsal)?