message: make rebase tests work
diff: @@ -210,9 +210,15 @@ export default class Store extends Source implements Syncable, Queryable, Updata
  let forkPoint = this._forkPoint;
  assert('A `base` store must be defined for `rebase` to work', !!base);
  - assert('A `forkPoint` must be defined for `rebase` to work', !!forkPoint);
  + //assert('A `forkPoint` must be defined for `rebase` to work', !!forkPoint);
  - let baseTransforms = base.transformsSince(forkPoint);
  + let baseTransforms: Transform[];
  + if (forkPoint === undefined){
  + // store was empty at fork point
  + baseTransforms = base.allTransforms();
  + } else {
  + baseTransforms = base.transformsSince(forkPoint);
  + }
  if (baseTransforms.length > 0) {
  let localTransforms = this.allTransforms();
  