diff --git a/mercurial/dagutil.py b/mercurial/dagutil.py
deleted file mode 100644
--- a/mercurial/dagutil.py
+++ /dev/null
@@ -1,49 +0,0 @@
-# dagutil.py - dag utilities for mercurial
-#
-# Copyright 2010 Benoit Boissinot <bboissin@gmail.com>
-# and Peter Arrenbrecht <peter@arrenbrecht.ch>
-#
-# This software may be used and distributed according to the terms of the
-# GNU General Public License version 2 or any later version.
-
-from __future__ import absolute_import
-
-from .node import nullrev
-
-from . import (
-    dagop,
-)
-
-class revlogdag(object):
-    '''dag interface to a revlog'''
-
-    def __init__(self, revlog):
-        self._revlog = revlog
-
-    def linearize(self, ixs):
-        '''linearize and topologically sort a list of revisions
-
-        The linearization process tries to create long runs of revs where
-        a child rev comes immediately after its first parent. This is done by
-        visiting the heads of the given revs in inverse topological order,
-        and for each visited rev, visiting its second parent, then its first
-        parent, then adding the rev itself to the output list.
-        '''
-        sorted = []
-        visit = list(dagop.headrevs(ixs, self._revlog.parentrevs))
-        visit.sort(reverse=True)
-        finished = set()
-
-        while visit:
-            cur = visit.pop()
-            if cur < 0:
-                cur = -cur - 1
-                if cur not in finished:
-                    sorted.append(cur)
-                    finished.add(cur)
-            else:
-                visit.append(-cur - 1)
-                visit += [p for p in self._revlog.parentrevs(cur)
-                          if p != nullrev and p in ixs and p not in finished]
-        assert len(sorted) == len(ixs)
-        return sorted