bug 517259, fix query in modelForSource to not check too many changes at once
bug 517259, fix query in modelForSource to not check too many changes at once

Pike/elmo,mozilla/elmo,mozilla/elmo,AdrianGaudebert/elmo,Pike/elmo,AdrianGaudebert/elmo,mozilla/elmo,mozilla/elmo,Pike/elmo,Pike/elmo,AdrianGaudebert/elmo