Suggestion: tool to derive version from github commit-id

[Mayuresh <mayuresh%acm.org@localhost>]

pkgsrc.txt has documented the procedure to version a github project based
on a commit tag. It describes both pre-first-release and
post-first-release scenarios.

I think it would be nice if url2pkg / pkglint could help automate the
above procedure.

-- 
Mayuresh