help: improve description of phases.checksubrepos setting The existing description was a bit hard to understand.

clone: do not turn hidden changeset public on publishing clone (issue3935) Before this changeset local clone of a repo with hidden changeset would include then in the clone (why not) and turn them public (plain wrong). This happened because the copy clone publish by dropping the phaseroot file entirely making everything in the repo public (and therefore immune to obsolescence marker). This changeset takes the simplest fix, we deny the copy clone in the case of hidden changeset falling back to pull clone that will exclude them from the clone and therefore not turning them public. A smarter version of copy clone could be done, but I prefer to go for the simplest solution first.