This mode is for projects that don't do ChangeLogs. Patcher won't try to create ChangeLog entries, and won't expect that you have written ChangeLog entries either.
Note that if you do have ChangeLog files in this mode, they will be regarded as ordinary source files. As a consequence, this is a case where it is not forbidden to list them explicitly as part of a subproject, although I don't see why you would want to do that.