qfinish: comply with the phases.new-commit option in secret mode (
issue3335)
In secret mode qfinished changeset were move to the draft phase in all case[1]
without regard to phases.new-commit value
This changeset ensure qfinish does not automatically promote a changeset
further than the phases.new-commit value.
Note: This may also result in qfinished changeset made public if
phases.new-commit is set to public.
[1] "In all case" where parent have a compatible phase. Qfinish keep never
altering phases of changeset not involved in the qfinish.