> But the xref seems present only in the master/v16/v15 patches, but not
> for the earlier patches v14/v13/v12. Why not?
I missed it.
> But the change was only in the patches v14 onwards. Although the new
> error message was only added for HEAD, isn't it still correct to say
> "A valid version is required." for all the patches including v12 and
> v13?
Yes, it's still correct.
Fixed versions are attached.