133   ** Unknown exception encountered with possibly-broken third-party extension evolve

   134   ** which supports versions 4.4 of Mercurial.

   135   ** Please disable evolve and try your action again.

   136   ** If that fixes the bug please report it to https://bz.mercurial-scm.org/

   137   ** Python 2.7.12 (default, Dec  4 2017, 14:50:18) [GCC 5.4.0 20160609]

   138   ** Mercurial Distributed SCM (version 4.5+64-87416288be98)

   139   ** Extensions loaded: rebase, evolve

   140   Traceback (most recent call last):

   141     File "/tmp/hgtests.vDbR61/install/bin/hg", line 41, in <module>

   142       dispatch.run()

   143     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/dispatch.py", line 88, in run

   144       status = (dispatch(req) or 0) & 255

   145     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/dispatch.py", line 183, in dispatch

   146       ret = _runcatch(req)

   147     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/dispatch.py", line 324, in _runcatch

   148       return _callcatch(ui, _runcatchfunc)

   149     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/dispatch.py", line 332, in _callcatch

   150       return scmutil.callcatch(ui, func)

   151     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/scmutil.py", line 154, in callcatch

   152       return func()

   153     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/dispatch.py", line 314, in _runcatchfunc

   154       return _dispatch(req)

   155     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/dispatch.py", line 918, in _dispatch

   156       cmdpats, cmdoptions)

   157     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/dispatch.py", line 673, in runcommand

   158       ret = _runcommand(ui, options, cmd, d)

   159     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/dispatch.py", line 926, in _runcommand

   160       return cmdfunc()

   161     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/dispatch.py", line 915, in <lambda>

   162       d = lambda: util.checksignature(func)(ui, *args, **strcmdopt)

   163     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/util.py", line 1195, in check

   164       return func(*args, **kwargs)

   165     File "/home/foobar/repo/mutable-history/hgext3rd/evolve/evolvecmd.py", line 1141, in evolve

   166       obsolete.createmarkers(repo, [(ctx, (repo[node],))])

   167     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/obsolete.py", line 1115, in createmarkers

   168       ui=repo.ui)

   169     File "/tmp/hgtests.vDbR61/install/lib/python/mercurial/obsolete.py", line 621, in create

   170       if len(succ) != 20:

   171   TypeError: object of type 'NoneType' has no len()

   172   [1]

   177   | *  7:ad0a59d83efe added e

   178   | |   () draft

   179   | x  6:2a4e03d422e2 added d

   180   |/    () draft