When adding group users after a search, the "Selected user's membership" field is wrong

When managing course group membership (via the 'Add/remove users' page), if you perform a search of 'Potential members' and then click on one of the returned users the 'Selected user's membership' field is not updated correctly.

It seems to continue using the index of the original users (before performing the search), as clicking on the second search result will display the groups of the second user in the list prior to the search.