sparse-revlog: add a `index_get_length` function in C
We are about to implement a native version of `slicechunktodensity`. For
clarity, we introduce the helper functions first. This new function provides
an efficient way to retrieve some of the information needed by
`slicechunktodensity`.
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)