Python: fix downgrade script

When new kinds are inserted, new indices exists that do not
correspond to any old indices.
These were previously mapped, now they are not.

Author: yoff

python/downgrades/503c0516fba2e5da9570f00eb34ef43025ecb8fb/py_exprs.ql

@@ -26,7 +26,12 @@ class ExprParent_ extends @py_expr_parent {
  */
 bindingset[new_index]
 int old_index(int new_index) {
-  if new_index < 18 then result = new_index else result + (19 - 18) = new_index
+  if new_index < 18
+  then result = new_index
+  else
+    if new_index >= 19
+    then result + (19 - 18) = new_index
+    else none()
 }
 
 // The schema for py_exprs is:

python/downgrades/503c0516fba2e5da9570f00eb34ef43025ecb8fb/py_stmts.ql

@@ -26,7 +26,12 @@ class StmtList_ extends @py_stmt_list {
  */
 bindingset[new_index]
 int old_index(int new_index) {
-  if new_index < 14 then result = new_index else result + (16 - 14) = new_index
+  if new_index < 14
+  then result = new_index
+  else
+    if new_index >= 16
+    then result + (16 - 14) = new_index
+    else none()
 }
 
 // The schema for py_stmts is: