Check for incorrect version strings (including an v at the beginning)

[JJ]

Some distributions have a version string that includes an v, but that is incorrect, since it creates a version that is, first, less than any version without the V (so if you need 0.0.1+ it will fail), and second, it explicitly includes the v in it.
So my proposal would be to check for those strings starting now, and flag them as incorrect.
Maybe run a test over existing distributions too, and create automatically issues and/or PRs.