use git-describe in bootstrap
use git-describe in bootstrap

``git describe --always`` is superior to ``git log`` in this case. It
generates a more useful version tag. For example, it allows a developer
building packages from the source tree to track and package unreleased
changes in a way that makes sense to package managers.

Using the --always flag reverts to the old behavior when no git tag is
resolvable from the current HEAD.

fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb,fkaempfer/couchdb