parseBranchingLogic concatenates arm and field

[gvds]

When a field is specified within a particular arm in branching logic (e.g. [screening_arm_4][co_enrol_report]), parseBranchingLogic concatenates these as 'screening_arm_4co_enrol_report' with the result that attempting to evaluate the rule (e.g. with(allrecords, eval(l)) ) returns an object not found error.