perf: start from an existing branchmap if possible If the --base set if a superset of one of the cached branchmap, we should use as a starting point. This greatly help the overall runtime of `hg perfbranchmapupdate` For example, for a repository with about 500 000 revisions, using this trick make the command runtime move from about 200 second to about 10 seconds. A 20x gain.

perf: rely on repoview for perfbranchmapupdate Using 'repoview' matching the base and target subset make the benchmark more realistic. It also unlocks optimization to make the command initialization faster.

perf: pre-indent some code in `perfbranchmapupdate` This make the next patch easier to read.

perf: add a `perfbranchmapupdate` command This command benchmark the time necessary to update the branchmap between two sets of revisions. This changeset introduce a first version, doing nothing fancy regarding cache or other internal details.

push: config option to control behavior when pushing to a publishing server Pushing to a publishing server by mistake can lead to a difficult situation to solve because evolution doesn't work on public changesets. This new experimental config tries to help avoiding unintentionally (or at least being aware of) pushing to publishing remotes. `hg push --publish` can be used to make push succeed even when auto-publish is set to 'abort'.

narrowcommands: remove an unrequired `repo.narrowpats` call We call that few lines above and do nothing significant in between which can change the narrowpats. So let's use values returned by that call. Differential Revision: https://phab.mercurial-scm.org/D5348

manifest: reject lines shorter than 42 bytes, not 22 Yuya correctly spotted during the review of f27f8e9ef1e73 that we're dealing with hexlified hashes here, and so it should be 42 bytes not 22. Differential Revision: https://phab.mercurial-scm.org/D5347