Previous Status condition: Immediately Previous setting cannot be disabled once enabled

To reproduce:

• Set up a "Checks the issue has been in a status previously" condition on a workflow transition and configure it to check only the immediately previous status.
• Save the condition config.
• Go back to the config edit page for the condition.

Expected behaviour: The "Immediately previous only" checkbox is checked, and unchecking it then saving the config will update the condition to check all previous statuses.

Actual behaviour: The checkbox is not checked, yet saving the config as-is will not update the condition.