This allows metav generated versions to be used as Docker image tags.
A tag name must be valid ASCII and may contain lowercase and uppercase letters, digits, underscores, periods and dashes. A tag name may not start with a period or a dash and may contain a maximum of 128 characters.
Source: https://docs.docker.com/engine/reference/commandline/tag/
Thanks for the PR.
I cherry pick the interesting commit (2c83104) onto master to avoid merging not useful commits among the five ones.
It's now included in Metav version 1.4.7.
This allows metav generated versions to be used as Docker image tags.