Python: DB upgrade script for default-indexing change

Follow this excellent guide:
https://github.com/github/codeql-c-extractor-team/blob/master/docs/db-upgrade.md

Author: RasmusWL

python/ql/src/semmlecode.python.dbscheme

@@ -5,6 +5,10 @@
  *      by adding rules to dbscheme.template
  */
 
+/* This is a dummy line to alter the dbscheme, so we can make a database upgrade
+ * 2020-05-04
+ */
+
  /*
  * External artifacts
  */
@@ -126,7 +130,7 @@ containerparent(int parent: @container ref,
                 unique int child: @container ref);
 
 @sourceline = @file | @py_Module | @xmllocatable;
- 
+
 numlines(int element_id: @sourceline ref,
          int num_lines: int ref,
          int num_code: int ref,
@@ -922,7 +926,7 @@ ext_rettype(int funcid : @py_object ref,
 ext_proptype(int propid : @py_object ref,
              int typeid : @py_object ref);
 
-ext_argreturn(int funcid : @py_object ref, 
+ext_argreturn(int funcid : @py_object ref,
               int arg : int ref);
 
 py_special_objects(unique int obj : @py_cobject ref,
@@ -935,15 +939,15 @@ py_decorated_object(int object : @py_object ref,
 
 @py_source_element = @py_ast_node | @container;
 
-/* XML Files */ 
+/* XML Files */
 
 xmlEncoding  (unique int id: @file ref, varchar(900) encoding: string ref);
 
 xmlDTDs       (unique int id: @xmldtd,
               varchar(900) root: string ref,
               varchar(900) publicId: string ref,
               varchar(900) systemId: string ref,
-              int fileid: @file ref); 
+              int fileid: @file ref);
 
 xmlElements   (unique int id: @xmlelement,
               varchar(900) name: string ref,
@@ -958,7 +962,7 @@ xmlAttrs      (unique int id: @xmlattribute,
               int idx: int ref,
               int fileid: @file ref);
 
-xmlNs         (int id: @xmlnamespace, 
+xmlNs         (int id: @xmlnamespace,
               varchar(900) prefixName: string ref,
               varchar(900) URI: string ref,
               int fileid: @file ref);
@@ -970,7 +974,7 @@ xmlHasNs      (int elementId: @xmlnamespaceable ref,
 xmlComments   (unique int id: @xmlcomment,
               varchar(3600) text: string ref,
               int parentid: @xmlparent ref,
-              int fileid: @file ref); 
+              int fileid: @file ref);
 
 xmlChars      (unique int id: @xmlcharacters,
               varchar(3600) text: string ref,