[Python-modules-team] Bug#949446: python3-ipython: Prevents sage fro starting, fails to import _baseclass_reprs

[Amaury Pouly]

Package: python3-ipython
Version: 7.11.1-1
Severity: important

Dear Maintainer,

Sagemath is not usable on my system because of an import error. I am not sure if the issue
lies with sage or with ipython. Here is the backtrace:

Traceback (most recent call last):
  File "/usr/lib/python3.7/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/lib/python3.7/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/usr/lib/python3/dist-packages/sage/repl/ipython_kernel/__main__.py", line 3, in <module>
    IPKernelApp.launch_instance(kernel_class=SageKernel)
  File "/usr/lib/python3/dist-packages/traitlets/config/application.py", line 663, in launch_instance
    app.initialize(argv)
  File "<decorator-gen-124>", line 2, in initialize
  File "/usr/lib/python3/dist-packages/traitlets/config/application.py", line 87, in catch_config_error
    return method(app, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/ipykernel/kernelapp.py", line 542, in initialize
    self.init_kernel()
  File "/usr/lib/python3/dist-packages/ipykernel/kernelapp.py", line 447, in init_kernel
    user_ns=self.user_ns,
  File "/usr/lib/python3/dist-packages/traitlets/config/configurable.py", line 412, in instance
    inst = cls(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/sage/repl/ipython_kernel/kernel.py", line 51, in __init__
    super(SageKernel, self).__init__(**kwds)
  File "/usr/lib/python3/dist-packages/ipykernel/ipkernel.py", line 68, in __init__
    kernel      = self,
  File "/usr/lib/python3/dist-packages/traitlets/config/configurable.py", line 412, in instance
    inst = cls(*args, **kwargs)
  File "/usr/lib/python3/dist-packages/IPython/core/interactiveshell.py", line 683, in __init__
    self.init_display_formatter()
  File "/usr/lib/python3/dist-packages/sage/repl/interpreter.py", line 231, in init_display_formatter
    backend.get_display_manager().switch_backend(backend, shell=self)
  File "/usr/lib/python3/dist-packages/sage/repl/rich_output/display_manager.py", line 322, in switch_backend
    self._backend.install(**kwds)
  File "/usr/lib/python3/dist-packages/sage/repl/rich_output/backend_ipython.py", line 59, in install
    from sage.repl.display.formatter import SageDisplayFormatter
  File "/usr/lib/python3/dist-packages/sage/repl/display/formatter.py", line 66, in <module>
    from sage.repl.display.pretty_print import SagePrettyPrinter
  File "/usr/lib/python3/dist-packages/sage/repl/display/pretty_print.py", line 29, in <module>
    from sage.repl.display.fancy_repr import *
  File "/usr/lib/python3/dist-packages/sage/repl/display/fancy_repr.py", line 17, in <module>
    from IPython.lib.pretty import (
ImportError: cannot import name '_baseclass_reprs' from 'IPython.lib.pretty' (/usr/lib/python3/dist-packages/IPython/lib/pretty.py)

-- System Information:
Debian Release: bullseye/sid
  APT prefers unstable
  APT policy: (500, 'unstable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 5.4.2-amdmp2 (SMP w/8 CPU cores)
Kernel taint flags: TAINT_OOT_MODULE, TAINT_UNSIGNED_MODULE
Locale: LANG=fr_FR.UTF-8, LC_CTYPE=fr_FR.UTF-8 (charmap=UTF-8), LANGUAGE=fr (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled

Versions of packages python3-ipython depends on:
ii  python3                 3.7.5-3
ii  python3-backcall        0.1.0-2
ii  python3-decorator       4.3.0-1.1
ii  python3-jedi            0.15.2-1
ii  python3-pexpect         4.6.0-1
ii  python3-pickleshare     0.7.5-1
ii  python3-pkg-resources   44.0.0-1
ii  python3-prompt-toolkit  2.0.10-2
ii  python3-pygments        2.3.1+dfsg-1
ii  python3-traitlets       4.3.3-2

python3-ipython recommends no packages.

python3-ipython suggests no packages.

-- no debconf information