issue #931: Fixes _rebuild_dict to give the correct index in the case of duplicate values.
Created originally on Bitbucket by zeripath (Andrew Thornton)
Changesets for this Pull Request have not been imported, because it had been already declined on Bitbucket. Marked as closed by the import user.
IndexedList._rebuild_dict was setting the incorrect index when there were duplicated values in the list. This fixes this, and in doing so resolves issue #931 (closed)