phases: extract the core of boundary retraction in '_retractboundary' At the moment the 'retractboundary' function is called for multiple reasons: First, actually retracting boundaries. There are only two cases for theses: 'hg phase --force' and 'hg qimport'. This will need extra graph computation to retrieve the phase changes. Second, setting the phases of newly added changesets. In this case we already know all the affected nodes and we just needs to register different information (old phase is None). Third, when reducing the set of roots when advancing phase. The phase are already properly tracked so we do not needs anything else in this case. To deal with this difference in phase tracking, we extract the core logic into a private method that all three cases can use.

phases: track phase movements in 'advanceboundary' Makes advanceboundary record the phase movement of affected revisions in tr.changes['phases']. The tracking is not usable yet because the 'retractboundary' function can also affect phases. We'll improve that in the coming changesets.