bookmarks: change bookmark within a transaction For some time, bookmark can and should be moved in the transaction. This changeset migrates the 'hg bookmarks' commands to use a transaction. Tests regarding rollback and transaction hooks are impacted for obvious reasons. Some have to be slightly updated to keep testing the same things. Some can just be dropped because they do not make sense anymore.

bookmark: remove the "touch changelog" hack Any changes to bookmarks used to touch the changelog to ensure hgweb was reloaded. This was fairly hacky and stops working when bookmarks are moved as part of the transaction. As hgweb is now explicitly tracking bookmark changes, we can remove this hack (and no tests break).

convert: add config option for disabling ancestor parent checks When converting merge commits, convert checks if any of the parents are ancestors of any of the other parents. To do this, it builds an ancestor list for every commit in the repository. On large repos this can take a long time (30min+). Let's add an option for disabling this check to preserve performance. The downside of this is that it may create unnecessary parent connections when enabled (which is unfortunate, but not incorrect). To verify, I ran the convert tests with the flag enabled, and verified the graph changes were all just to add new parents that were ancestors of existing parents.