strip: introduce a soft strip option
This is the first user-accessible way to use the archived phase introduced in
4.8. This implements a feature discussed during the Stockholm sprint, using
the archived phase for hiding changesets.
The archived phase behaves exactly as stripping: changesets are no longer
visible, but pulling/unbundling them will make then reappear. The only notable
difference is that unlike hard stripping, soft stripping does not affect
obsmarkers.
The next changeset will make use of the archived phase for history rewriting
command. However, having a way to manually trigger the feature first seems a
necessary step before exposing users to this phase; there is a way to
un-archived changesets (unbundling), so there must be a way to archive them
again.
Adding a flag to strip is a good way to provide access to the feature without
taking a too big risk on the final UI we want. The flag is experimental so it
won't be exposed by default.
Using the archived phase is faster and less traumatic for the repository than
actually stripping changesets.
#require docutils gettext
$ $TESTDIR/check-gendoc sv
checking for parse errors