When attempting to clear the patient program completion date from the patient dashboard, when I select everything in the Completion Date field, and delete it, when I try to save it, it gives a popup message which says "A completion date cannot be before an enrollment date". As a work around, you can delete the enrollment date and the completion date, and it will allow you to save it. But, when you try to open it again to enter the enrollment date, it gives the same error "A completion date cannot be before an enrollment date", even with the completion date left blank.
This happens with OpenMRS Version: 1.9.0 RC Build 26313. This is a new bug with OpenMRS 1.9, as it works properly in the web demo of OpenMRS, Version: 1.8.2 Build 26400.