IDManagement: fix missing WM name validation when using "keep current WM list" code path

The blendfile_liblink and blendfile_io python tests in debug fired an
assert that WMWinMan object was in Main database, but not in the ID
name map. This was caused by wm_window_match_do going into case 3
there: the new WM list is completely empty, the old list is not empty,
and it was directly using the old/current list (via
wm_window_match_keep_current_wm function), without actually
registering/validating the objects in it through the name map.

Reviewed By: Bastien Montagne
Differential Revision: https://developer.blender.org/D15787

source/blender/windowmanager/intern/wm_files.c

@@ -296,6 +296,12 @@ static void wm_window_match_keep_current_wm(const bContext *C,
     }
   }
 
+  /* we'll be using the current wm list directly; make sure
+   * the names are validated and in the name map. */
+  LISTBASE_FOREACH (wmWindowManager *, wm_item, current_wm_list) {
+    BKE_main_namemap_get_name(bmain, &wm_item->id, wm_item->id.name + 2);
+  }
+
   *r_new_wm_list = *current_wm_list;
 }