Search Builder incorrect result upon searching for contacts NOT in a group

When using the Search Builder to search for contacts who are NOT in a certain group, the Search Builder returns incorrect results.

Steps to reproduce:
1. Go to the Search Builder
2. For record type, select Contact
3. For field, select Group(s)
4. Choose the ≠ operator
5. Select a group. I tried it with the Newsletter Subscribers group on http://wp46.demo.civicrm.org/

Result:
The Search Builder adds a search criterion that was not specified, namely the Group Status criterion. So the search becomes: Group(s) ≠ Newsletter Subscribers ...AND... Group Status "Added". Due to this, some people who ARE in the Newsletter Subscribers group appear in the search results.

Expected result:
The search should be Group(s) ≠ Newsletter Subscribers only, without any other clauses added.

See related SE question: http://civicrm.stackexchange.com/questions/8085/how-to-search-for-contacts-not-in-a-group-through-the-search-builder/8087