diff -r 8e38fa360a12 -r db30c6bfeb70 mercurial/commands.py
--- a/mercurial/commands.py	Thu Feb 02 10:04:55 2017 +0100
+++ b/mercurial/commands.py	Thu Feb 02 10:05:22 2017 +0100
@@ -1854,60 +1854,6 @@
     with repo.wlock(False):
         return cmdutil.copy(ui, repo, pats, opts)
 
-@command('debugsuccessorssets',
-    [],
-    _('[REV]'))
-def debugsuccessorssets(ui, repo, *revs):
-    """show set of successors for revision
-
-    A successors set of changeset A is a consistent group of revisions that
-    succeed A. It contains non-obsolete changesets only.
-
-    In most cases a changeset A has a single successors set containing a single
-    successor (changeset A replaced by A').
-
-    A changeset that is made obsolete with no successors are called "pruned".
-    Such changesets have no successors sets at all.
-
-    A changeset that has been "split" will have a successors set containing
-    more than one successor.
-
-    A changeset that has been rewritten in multiple different ways is called
-    "divergent". Such changesets have multiple successor sets (each of which
-    may also be split, i.e. have multiple successors).
-
-    Results are displayed as follows::
-
-        <rev1>
-            <successors-1A>
-        <rev2>
-            <successors-2A>
-            <successors-2B1> <successors-2B2> <successors-2B3>
-
-    Here rev2 has two possible (i.e. divergent) successors sets. The first
-    holds one element, whereas the second holds three (i.e. the changeset has
-    been split).
-    """
-    # passed to successorssets caching computation from one call to another
-    cache = {}
-    ctx2str = str
-    node2str = short
-    if ui.debug():
-        def ctx2str(ctx):
-            return ctx.hex()
-        node2str = hex
-    for rev in scmutil.revrange(repo, revs):
-        ctx = repo[rev]
-        ui.write('%s\n'% ctx2str(ctx))
-        for succsset in obsolete.successorssets(repo, ctx.node(), cache):
-            if succsset:
-                ui.write('    ')
-                ui.write(node2str(succsset[0]))
-                for node in succsset[1:]:
-                    ui.write(' ')
-                    ui.write(node2str(node))
-            ui.write('\n')
-
 @command('debugtemplate',
     [('r', 'rev', [], _('apply template on changesets'), _('REV')),
      ('D', 'define', [], _('define template keyword'), _('KEY=VALUE'))],