Fix duplicate brushes from recent startup files

Default versioning caused duplicates when the startup was re-saved.

See c305759762

source/blender/blenloader/intern/versioning_280.c

@@ -2783,6 +2783,11 @@ void blo_do_versions_280(FileData *fd, Library *UNUSED(lib), Main *bmain)
 		}
 	}
 
+	if (!MAIN_VERSION_ATLEAST(bmain, 280, 43)) {
+		ListBase *lb = which_libbase(bmain, ID_BR);
+		BKE_main_id_repair_duplicate_names_listbase(lb);
+	}
+
 	{
 		/* Versioning code until next subversion bump goes here. */
 	}