Fix an issue where repositories with hyphens could sort improperly in typeaheads

Summary: Fixes T12894. See that task for discussion.

Test Plan:

• Created repositories abcdef, then abcdef-a through abcdef-f.
• Before patch, awkward sort order.
• After patch, query for abcdef hits abcdef first.
• See T12894 for details and screenshots.

Reviewers: chad, amckinley

Reviewed By: chad

Maniphest Tasks: T12894

Differential Revision: https://secure.phabricator.com/D18179