Companion for #7789 (BabeApi::current_epoch) (#2170)
* point to branch * update babe API implementations * build * Revert "point to branch" This reverts commit 669fde1e. * update Cargo.lock * bump
* point to branch * update babe API implementations * build * Revert "point to branch" This reverts commit 669fde1e. * update Cargo.lock * bump