--- a/hgext3rd/topic/__init__.py	Mon Sep 11 17:24:33 2017 +0200
+++ b/hgext3rd/topic/__init__.py	Sun Sep 10 22:41:54 2017 +0900
@@ -79,6 +79,7 @@
 )
 
 from . import (
+    compat,
     constants,
     revset as topicrevset,
     destination,
@@ -727,16 +728,6 @@
             fm.plain('\n')
     fm.end()
 
-getmarkers = None
-try:
-    from mercurial import obsutil
-    getmarkers = getattr(obsutil, 'getmarkers', None)
-except ImportError:
-    pass
-
-if getmarkers is None:
-    getmarkers = obsolete.getmarkers
-
 def _getlasttouched(repo, topics):
     """
     Calculates the last time a topic was used. Returns a dictionary of seconds
@@ -758,7 +749,7 @@
                 maxtime = rt
             # looking on the markers also to get more information and accurate
             # last touch time.
-            obsmarkers = getmarkers(repo, [repo[revs].node()])
+            obsmarkers = compat.getmarkers(repo, [repo[revs].node()])
             for marker in obsmarkers:
                 rt = marker.date()
                 if rt[0] > maxtime[0]:

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hgext3rd/topic/compat.py	Sun Sep 10 22:41:54 2017 +0900
@@ -0,0 +1,24 @@
+# Copyright 2017 FUJIWARA Katsunori <foozy@lares.dti.ne.jp>
+#
+# This software may be used and distributed according to the terms of the
+# GNU General Public License version 2 or any later version.
+"""
+Compatibility module
+"""
+from __future__ import absolute_import
+
+from mercurial import obsolete
+
+getmarkers = None
+successorssets = None
+try:
+    from mercurial import obsutil
+    getmarkers = getattr(obsutil, 'getmarkers', None)
+    successorssets = getattr(obsutil, 'successorssets', None)
+except ImportError:
+    pass
+
+if getmarkers is None:
+    getmarkers = obsolete.getmarkers
+if successorssets is None:
+    successorssets = obsolete.successorssets

--- a/hgext3rd/topic/evolvebits.py	Mon Sep 11 17:24:33 2017 +0200
+++ b/hgext3rd/topic/evolvebits.py	Sun Sep 10 22:41:54 2017 +0900
@@ -1,15 +1,6 @@
 import collections
-from mercurial import obsolete
 
-successorssets = None
-try:
-    from mercurial import obsutil
-    successorssets = getattr(obsutil, 'successorssets', None)
-except ImportError:
-    pass
-
-if successorssets is None:
-    successorssets = obsolete.successorssets
+from . import compat
 
 # Copied from evolve 081605c2e9b6
 
@@ -82,14 +73,14 @@
         return p.rev()
     obs = repo[p]
     ui = repo.ui
-    newer = successorssets(repo, obs.node())
+    newer = compat.successorssets(repo, obs.node())
     # search of a parent which is not killed
     while not newer:
         ui.debug("stabilize target %s is plain dead,"
                  " trying to stabilize on its parent\n" %
                  obs)
         obs = obs.parents()[0]
-        newer = successorssets(repo, obs.node())
+        newer = compat.successorssets(repo, obs.node())
     if len(newer) > 1 or len(newer[0]) > 1:
         raise MultipleSuccessorsError(newer)