Originally it was detected that moving from weeklies to on-demand (before beta) leaded to a incorrect "dev+" version, ultimately breaking when we released beta.

Also, we have decided that, once we are in releases candidates, only release candidates or final versions will be allowed (aka we won't allow on-demand at that stage).

So this is about:

1) ensure that on-demand applied to "dev" does not add the "+" ever. But continues having own "on-demand" commit message.
2) ensure that on-demand applied to "rcN" versions is not allowed.
3) and confirm that on-demand applied to "beta" does continue adding the "+" and commit message as is now.