Error thrown while running "hg debugext"

~$ hg debugext
*** failed to import extension hggit: No module named 'hggit'
extension hggit not activated!
absorb
churn
convert
evolve (5.6!)
extdiff
hgfluiddyn** Unknown exception encountered with possibly-broken third-party extension hgfluiddyn
** which supports versions 5.2 of Mercurial.
** Please disable hgfluiddyn and try your action again.
** If that fixes the bug please report it to https://foss.heptapod.net/fluiddyn/hg-fluiddyn/issues
** Python 3.6.9 (default, Oct  8 2020, 12:12:24) [GCC 8.4.0]
** Mercurial Distributed SCM (version 5.6.1)
** Extensions loaded: pager, churn, rebase, purge, strip, extdiff, convert, evolve, topic, absorb, hgfluiddyn
Traceback (most recent call last):
  File "/home/avmo/.local/pipx/venvs/mercurial/bin/hg", line 43, in <module>
    dispatch.run()
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/mercurial/dispatch.py", line 113, in run
    status = dispatch(req)
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/mercurial/dispatch.py", line 303, in dispatch
    ret = _runcatch(req) or 0
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/mercurial/dispatch.py", line 479, in _runcatch
    return _callcatch(ui, _runcatchfunc)
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/mercurial/dispatch.py", line 488, in _callcatch
    return scmutil.callcatch(ui, func)
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/mercurial/scmutil.py", line 153, in callcatch
    return func()
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/mercurial/dispatch.py", line 469, in _runcatchfunc
    return _dispatch(req)
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/mercurial/dispatch.py", line 1233, in _dispatch
    lui, repo, cmd, fullargs, ui, options, d, cmdpats, cmdoptions
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/mercurial/dispatch.py", line 917, in runcommand
    ret = _runcommand(ui, options, cmd, d)
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/hgext/pager.py", line 76, in pagecmd
    return orig(ui, options, cmd, cmdfunc)
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/mercurial/dispatch.py", line 1244, in _runcommand
    return cmdfunc()
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/mercurial/dispatch.py", line 1230, in <lambda>
    d = lambda: util.checksignature(func)(ui, *args, **strcmdopt)
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/mercurial/util.py", line 1867, in check
    return func(*args, **kwargs)
  File "/home/avmo/.local/pipx/venvs/mercurial/lib/python3.6/site-packages/mercurial/debugcommands.py", line 1115, in debugextensions
    fm.plain(b' (%s!)\n' % lasttestedversion)
TypeError: %b requires a bytes-like object, or an object that implements __bytes__, not 'str'

~$ hg version
*** failed to import extension hggit: No module named 'hggit'
extension hggit not activated!
Mercurial Distributed SCM (version 5.6.1)
(see https://mercurial-scm.org for more information)

Copyright (C) 2005-2020 Matt Mackall and others
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

~$ python --version
Python 3.6.9