Fix [2790959] Document Date not updating Period as it did in Compiere (commit 2 of 2)

Callouts are being called twice
Link to SF Tracker: http://sourceforge.net/support/tracker.php?aid=2790959

base/src/org/compiere/model/GridTab.java

@@ -2570,7 +2570,7 @@ public class GridTab implements DataStatusListener, Evaluatee, Serializable
 		int col = m_mTable.findColumn(field.getColumnName());
 		m_mTable.setValueAt(value, m_currentRow, col, false);
 		//
-		return processFieldChange (field);
+		return ""; // processFieldChange (field); // here we don't need to call processFieldChange, it was called on GridController.dataStatusChanged
 	}   //  setValue
 
 	/**