--- a/hgext3rd/topic/__init__.py	Fri Mar 16 14:59:10 2018 +0530
+++ b/hgext3rd/topic/__init__.py	Fri Mar 16 15:01:44 2018 +0530
@@ -134,13 +134,14 @@
 from . import (
     compat,
     constants,
+    destination,
+    discovery,
+    evolvebits,
     flow,
+    randomname,
     revset as topicrevset,
-    destination,
     stack,
     topicmap,
-    discovery,
-    randomname
 )
 
 if util.safehasattr(registrar, 'command'):
@@ -240,6 +241,10 @@
     revlist = stack.stack(self._repo, topic=topic)
     try:
         return revlist.index(self.rev())
+    except ValueError:
+        if self.obsolete():
+            succ = evolvebits._singlesuccessor(self._repo, self)
+            return revlist.index(succ)
     except IndexError:
         # Lets move to the last ctx of the current topic
         return None

--- a/tests/test-evolve-topic.t	Fri Mar 16 14:59:10 2018 +0530
+++ b/tests/test-evolve-topic.t	Fri Mar 16 15:01:44 2018 +0530
@@ -324,47 +324,5 @@
   ~
 
   $ hg prev
-  ** Unknown exception encountered with possibly-broken third-party extension evolve
-  ** which supports versions 4.4 of Mercurial.
-  ** Please disable evolve and try your action again.
-  ** If that fixes the bug please report it to https://bz.mercurial-scm.org/
-  ** Python 2.7.12 (default, Dec  4 2017, 14:50:18) [GCC 5.4.0 20160609]
-  ** Mercurial Distributed SCM (version 4.5.2+1098-cdc73e5c75af)
-  ** Extensions loaded: rebase, evolve, topic
-  Traceback (most recent call last):
-    File "/tmp/hgtests.GW4RZg/install/bin/hg", line 41, in <module>
-      dispatch.run()
-    File "/tmp/hgtests.GW4RZg/install/lib/python/mercurial/dispatch.py", line 88, in run
-      status = (dispatch(req) or 0)
-    File "/tmp/hgtests.GW4RZg/install/lib/python/mercurial/dispatch.py", line 208, in dispatch
-      ret = _runcatch(req)
-    File "/tmp/hgtests.GW4RZg/install/lib/python/mercurial/dispatch.py", line 349, in _runcatch
-      return _callcatch(ui, _runcatchfunc)
-    File "/tmp/hgtests.GW4RZg/install/lib/python/mercurial/dispatch.py", line 357, in _callcatch
-      return scmutil.callcatch(ui, func)
-    File "/tmp/hgtests.GW4RZg/install/lib/python/mercurial/scmutil.py", line 154, in callcatch
-      return func()
-    File "/tmp/hgtests.GW4RZg/install/lib/python/mercurial/dispatch.py", line 339, in _runcatchfunc
-      return _dispatch(req)
-    File "/tmp/hgtests.GW4RZg/install/lib/python/mercurial/dispatch.py", line 943, in _dispatch
-      cmdpats, cmdoptions)
-    File "/tmp/hgtests.GW4RZg/install/lib/python/mercurial/dispatch.py", line 700, in runcommand
-      ret = _runcommand(ui, options, cmd, d)
-    File "/tmp/hgtests.GW4RZg/install/lib/python/mercurial/dispatch.py", line 951, in _runcommand
-      return cmdfunc()
-    File "/tmp/hgtests.GW4RZg/install/lib/python/mercurial/dispatch.py", line 940, in <lambda>
-      d = lambda: util.checksignature(func)(ui, *args, **strcmdopt)
-    File "/tmp/hgtests.GW4RZg/install/lib/python/mercurial/util.py", line 1497, in check
-      return func(*args, **kwargs)
-    File "/home/foobar/repo/mutable-history/hgext3rd/evolve/__init__.py", line 1052, in cmdprevious
-      opts.get('move_bookmark'), topic)
-    File "/home/foobar/repo/mutable-history/hgext3rd/evolve/__init__.py", line 995, in _findprevtarget
-      if currenttopic and topic and _gettopicidx(p1) != 1:
-    File "/home/foobar/repo/mutable-history/hgext3rd/evolve/__init__.py", line 957, in _gettopicidx
-      return getattr(ctx, 'topicidx', lambda: None)()
-    File "/home/foobar/repo/mutable-history/hgext3rd/topic/__init__.py", line 242, in _contexttopicidx
-      return revlist.index(self.rev())
-    File "/home/foobar/repo/mutable-history/hgext3rd/topic/stack.py", line 95, in index
-      return self.revs.index(item)
-  ValueError: 15 is not in list
-  [1]
+  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
+  [14] add ggg