topicmap: write and read format from disc To prevent too awful performance we allow writing and reading topicmap cache. This is done with a lot of code duplication from core because core is not extensible enough.

topicmap: ensure that 'served' view is updated with topicmap There is multiple place that explicitly update the 'served' branchmap to ensure it stay up to date. We ensure it use the proper topicmap in this case.

topicmap: move the monkey patching into a context manager There is a couple of other place doing branchmap/topicmap update (of the served set), we'll have to set the monkey patching for them. This changeset is just doing the move to a context manager to make sure it is correct.

push: hackish handeling of new branch head from phase move The current head checking mechanism is not expecting "head change" from phase movement. Topic allows that, changeset with a topic moving to public can create a new head. We introduce a hack to double check that no head were added at the transaction level to work around this.