Fix (unreported): crash on undo when using pinned id in spreadsheet

Now the behavior is the same as in the properties editor, as far as I can tell.

release/scripts/startup/bl_operators/spreadsheet.py

@@ -24,7 +24,7 @@ class SPREADSHEET_OT_toggle_pin(bpy.types.Operator):
     '''Turn on or off pinning'''
     bl_idname = "spreadsheet.toggle_pin"
     bl_label = "Toggle Pin"
-    bl_options = {'REGISTER', 'UNDO'}
+    bl_options = {'REGISTER'}
 
     @classmethod
     def poll(cls, context):

source/blender/blenloader/intern/readfile.c

@@ -2985,6 +2985,12 @@ static void lib_link_workspace_layout_restore(struct IDNameLib_Map *id_map,
 
           sclip->scopes.ok = 0;
         }
+        else if (sl->spacetype == SPACE_SPREADSHEET) {
+          SpaceSpreadsheet *sspreadsheet = (SpaceSpreadsheet *)sl;
+
+          sspreadsheet->pinned_id = restore_pointer_by_name(
+              id_map, sspreadsheet->pinned_id, USER_IGNORE);
+        }
       }
     }
   }