lichray

"""Calculate the current package version number based on git tags.

If possible, use the output of `git describe` modified to conform to the
versioning scheme that setuptools uses (see PEP 386).  Releases must be
labelled with annotated tags (signed tags are annotated) of the following
format:

    v<num>(.<num>)+ [ {a|b|c|rc} <num> (.<num>)* ]

If `git describe` returns an error (likely because we're in an unpacked copy