--- a/mercurial/debugcommands.py	Wed Feb 01 17:42:49 2017 +0100
+++ b/mercurial/debugcommands.py	Wed Feb 01 17:46:21 2017 +0100
@@ -41,6 +41,7 @@
     localrepo,
     lock as lockmod,
     merge as mergemod,
+    obsolete,
     policy,
     pycompat,
     repair,
@@ -1237,6 +1238,117 @@
     ui.write('\n'.join(sorted(completions)))
     ui.write('\n')
 
+@command('debugobsolete',
+        [('', 'flags', 0, _('markers flag')),
+         ('', 'record-parents', False,
+          _('record parent information for the precursor')),
+         ('r', 'rev', [], _('display markers relevant to REV')),
+         ('', 'index', False, _('display index of the marker')),
+         ('', 'delete', [], _('delete markers specified by indices')),
+        ] + commands.commitopts2 + commands.formatteropts,
+         _('[OBSOLETED [REPLACEMENT ...]]'))
+def debugobsolete(ui, repo, precursor=None, *successors, **opts):
+    """create arbitrary obsolete marker
+
+    With no arguments, displays the list of obsolescence markers."""
+
+    def parsenodeid(s):
+        try:
+            # We do not use revsingle/revrange functions here to accept
+            # arbitrary node identifiers, possibly not present in the
+            # local repository.
+            n = bin(s)
+            if len(n) != len(nullid):
+                raise TypeError()
+            return n
+        except TypeError:
+            raise error.Abort('changeset references must be full hexadecimal '
+                             'node identifiers')
+
+    if opts.get('delete'):
+        indices = []
+        for v in opts.get('delete'):
+            try:
+                indices.append(int(v))
+            except ValueError:
+                raise error.Abort(_('invalid index value: %r') % v,
+                                  hint=_('use integers for indices'))
+
+        if repo.currenttransaction():
+            raise error.Abort(_('cannot delete obsmarkers in the middle '
+                                'of transaction.'))
+
+        with repo.lock():
+            n = repair.deleteobsmarkers(repo.obsstore, indices)
+            ui.write(_('deleted %i obsolescence markers\n') % n)
+
+        return
+
+    if precursor is not None:
+        if opts['rev']:
+            raise error.Abort('cannot select revision when creating marker')
+        metadata = {}
+        metadata['user'] = opts['user'] or ui.username()
+        succs = tuple(parsenodeid(succ) for succ in successors)
+        l = repo.lock()
+        try:
+            tr = repo.transaction('debugobsolete')
+            try:
+                date = opts.get('date')
+                if date:
+                    date = util.parsedate(date)
+                else:
+                    date = None
+                prec = parsenodeid(precursor)
+                parents = None
+                if opts['record_parents']:
+                    if prec not in repo.unfiltered():
+                        raise error.Abort('cannot used --record-parents on '
+                                         'unknown changesets')
+                    parents = repo.unfiltered()[prec].parents()
+                    parents = tuple(p.node() for p in parents)
+                repo.obsstore.create(tr, prec, succs, opts['flags'],
+                                     parents=parents, date=date,
+                                     metadata=metadata)
+                tr.close()
+            except ValueError as exc:
+                raise error.Abort(_('bad obsmarker input: %s') % exc)
+            finally:
+                tr.release()
+        finally:
+            l.release()
+    else:
+        if opts['rev']:
+            revs = scmutil.revrange(repo, opts['rev'])
+            nodes = [repo[r].node() for r in revs]
+            markers = list(obsolete.getmarkers(repo, nodes=nodes))
+            markers.sort(key=lambda x: x._data)
+        else:
+            markers = obsolete.getmarkers(repo)
+
+        markerstoiter = markers
+        isrelevant = lambda m: True
+        if opts.get('rev') and opts.get('index'):
+            markerstoiter = obsolete.getmarkers(repo)
+            markerset = set(markers)
+            isrelevant = lambda m: m in markerset
+
+        fm = ui.formatter('debugobsolete', opts)
+        for i, m in enumerate(markerstoiter):
+            if not isrelevant(m):
+                # marker can be irrelevant when we're iterating over a set
+                # of markers (markerstoiter) which is bigger than the set
+                # of markers we want to display (markers)
+                # this can happen if both --index and --rev options are
+                # provided and thus we need to iterate over all of the markers
+                # to get the correct indices, but only display the ones that
+                # are relevant to --rev value
+                continue
+            fm.startitem()
+            ind = i if opts.get('index') else None
+            cmdutil.showmarker(fm, m, index=ind)
+        fm.end()
+
 @command('debugupgraderepo', [
     ('o', 'optimize', [], _('extra optimization to perform'), _('NAME')),
     ('', 'run', False, _('performs an upgrade')),