Github Group

[Sean Farley]

I wanted to revisit and close this ticket I started almost a year ago:

https://trac.macports.org/ticket/33889

I think it'll suffice to check for a tarball download + an empty tag
prefix + len(version) > 12. A hash can be looked up at any length as
long as it's match is unique, therefore the length of 12 is a soft
requirement. I didn't pull it out of thin air, though; it's from an
early version of git / mercurial of making 12 a lower bound until
better algorithms arose.

Does this sound ok? If so, then I can commit my changes and close the ticket.