http://git.sugarlabs.org/calculate/mainline/merge_requests/10
https://bugs.sugarlabs.org/ticket/2697

• prove the source code changes are not present now,
• prove the fix is not present now in some other form,
• describe a test case,
• merge the fix,
• verify the test case,
• make a pull request,
• close the ticket 2697, and/or 4814.