Fix #22816: crash in depsgraph loading some 2.49 files, tagging objects for

update on load should be done later because it's not known yet which scene
is used with which layers visible before the windows are created.

source/blender/blenkernel/intern/blender.c

@@ -313,8 +313,6 @@ static void setup_app_data(bContext *C, BlendFileData *bfd, char *filename)
 
 	/* baseflags, groups, make depsgraph, etc */
 	set_scene_bg(CTX_data_scene(C));
-
-	DAG_on_load_update();
 	
 	MEM_freeN(bfd);
 }
@@ -478,6 +476,9 @@ static int read_undosave(bContext *C, UndoElem *uel)
 	strcpy(G.sce, scestr);
 	G.fileflags= fileflags;
 
+	if(success)
+		DAG_on_load_update();
+
 	return success;
 }
 

source/blender/blenkernel/intern/depsgraph.c

@@ -2217,7 +2217,7 @@ static void dag_current_scene_layers(Main *bmain, Scene **sce, unsigned int *lay
 		*sce= bmain->scene.first;
 		if(*sce) *lay= (*sce)->lay;
 
-		/* XXX for background mode, we should get the scen
+		/* XXX for background mode, we should get the scene
 		   from somewhere, for the -S option, but it's in
 		   the context, how to get it here? */
 	}
@@ -2248,7 +2248,7 @@ void DAG_on_load_update(void)
 
 	dag_current_scene_layers(bmain, &scene, &lay);
 
-	if(scene) {
+	if(scene && scene->theDag) {
 		/* derivedmeshes and displists are not saved to file so need to be
 		   remade, tag them so they get remade in the scene update loop,
 		   note armature poses or object matrices are preserved and do not

source/blender/windowmanager/intern/wm_files.c

@@ -61,6 +61,7 @@
 
 #include "BKE_blender.h"
 #include "BKE_context.h"
+#include "BKE_depsgraph.h"
 #include "BKE_DerivedMesh.h"
 #include "BKE_exotic.h"
 #include "BKE_font.h"
@@ -309,7 +310,9 @@ void WM_read_file(bContext *C, char *name, ReportList *reports)
 //		refresh_interface_font();
 
 		CTX_wm_window_set(C, CTX_wm_manager(C)->windows.first);
+
 		ED_editors_init(C);
+		DAG_on_load_update();
 
 #ifndef DISABLE_PYTHON
 		/* run any texts that were loaded in and flagged as modules */
@@ -389,6 +392,7 @@ int WM_read_homefile(bContext *C, wmOperator *op)
 	BKE_write_undo(C, "original");	/* save current state */
 
 	ED_editors_init(C);
+	DAG_on_load_update();
 	
 	WM_event_add_notifier(C, NC_WM|ND_FILEREAD, NULL);
 	CTX_wm_window_set(C, NULL); /* exits queues */