This script attempts to generate a useful version number
in a git or mercurial repository using tags, revisions and
dirtiness.  For example, consider a simple untagged repo:

    $ mkdir foo
    $ cd foo
    $ git init
    $ touch README
    $ git add README
    $ git commit -m "first commit"
    $ tagver
    0.0.ffbcc93

If there aren't any tags in a repo, tagver prepends 0.0 to
the changeset number.  Now let's tag a revision for release
and try again:

    $ git tag v1.0
    $ tagver
    1.0

If there's a "v" on the front of the tag, tagver assumes
it's extraneous. Now add an untagged revision:

    $ echo >> README
    $ git commit -am "second commit"
    $ tagver
    1.0.1.gad8eb1e

and another:

    $ echo >> README
    $ git commit -am "third commit"
    $ tagver
    1.0.2.g621c4f3

You get the idea. What happens if we have uncommitted
changes lying around?

    $ echo >> README
    $ tagver
    1.0.2.g621c4f3+

Note the trailing + indicating a dirty working directory.
And now let's make a new release:

    $ git commit -am "fourth commit"
    $ git tag v1.1
    $ tagver
    1.1

vim: tw=60