un-fork go-memdb
commit 9322636c8926f155a10d9679e364e3f8e86203d6
temporarily switched to a fork of go-memdb, because
a pull request that was needed was not yet merged
upstream.
this pull request was merged, so we can un-fork
this dependency.
this change does not bump the dependency, and
only un-forks. bumping the dependency should
be done in a separate change, if needed.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
(cherry picked from commit 5f057f6350364d93b5e32ad205a492f399ce1cd3)
Signed-off-by: Victor Vieux <vieux@docker.com>