head-checking: ignore obsoleted section when checking head creation locally Same as for the server side check, these do not need to be taken in account.

head-checking: ignore obsolete section when checking for single heads This overwrite the core code that enforce single heads to ignore obsolete section. That way older obsolete version of a branch no longer prevent the new version to be pushed.

head-checking: update changelog

head-checking: add test variant mixing branch and topics