In order to fix a bug in version: https://rt.cpan.org/Ticket/Display.html?id=93340 the behavior of normal() on dotted-decimal alpha versions, e.g. "v1.2.3_1", was changed to emit a warning that this was a lossy method and render it as "v18.104.22.168". Using stringify() instead will ensure that the original representation is returned (with the underscore), so that M::B's own heuristic to determine whether the release_status is unstable to continue working. Alternatively, keeping the version object, instead of jamming it into a string, you could use the is_alpha() object method instead.
What MBTest did was never right, but broke completely when TB changed. This makes it significantly more sane.