Fix crash creating new file after modifications

Seems to be caused by cae3750 which changed free() function used
by bmain free to the one which does dependency graph tag. We do
no want to do any tags here.

source/blender/blenkernel/intern/main.c

@@ -65,7 +65,10 @@ void BKE_main_free(Main *mainvar)
 	int a;
 
 	/* Since we are removing whole main, no need to bother 'properly' (and slowly) removing each ID from it. */
-	const int free_flag = LIB_ID_FREE_NO_MAIN | LIB_ID_FREE_NO_UI_USER | LIB_ID_FREE_NO_USER_REFCOUNT;
+	const int free_flag = (LIB_ID_FREE_NO_MAIN |
+	                       LIB_ID_FREE_NO_UI_USER |
+	                       LIB_ID_FREE_NO_USER_REFCOUNT |
+	                       LIB_ID_FREE_NO_DEG_TAG);
 
 	MEM_SAFE_FREE(mainvar->blen_thumb);