Virtaal is broken out-of-the-box on Ubuntu 20.04 LTS

Virtaal is totally broken and cannot be used to modify .po files on Ubuntu 20.04 LTS.

The biggest problem seems to be missing following line in /usr/lib/python3/dist-packages/virtaal/support/set_enumerator.py:

    from functools import reduce

This line is needed before reduce() is used because Guido van van Rossum didn't like it and forced to move it to another namespace.

Even if that's fixed, there are so many other problems that Virtaal cannot be used to actually modify .po files in practice. If you open it in a terminal and look at the terminal output, you'll surely see it.

Some examples:

NameError: name 'reduce' is not defined
/usr/lib/python3/dist-packages/gi/overrides/Gtk.py:1632: Warning: g_value_type_compatible: assertion 'src_type' failed
  return _Gtk_main(*args, **kwargs)
/usr/lib/python3/dist-packages/virtaal/views/mainview.py:551: Warning: g_value_type_compatible: assertion 'src_type' failed
  Gtk.main_iteration()

ERROR:root:Failed to start TM server
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/virtaal/plugins/tm/models/localtm.py", line 78, in __init__
    self.tmserver = subprocess.Popen(command)
  File "/usr/lib/python3.8/subprocess.py", line 858, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/usr/lib/python3.8/subprocess.py", line 1704, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: 'tmserver'
ERROR:root:Failed to load plugin "localtm"
[Errno 2] No such file or directory: 'tmserver'
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/virtaal/controllers/plugincontroller.py", line 117, in enable_plugin
    self.plugins[name] = plugin_class(name, self.controller)
  File "/usr/lib/python3/dist-packages/virtaal/plugins/tm/models/localtm.py", line 78, in __init__
    self.tmserver = subprocess.Popen(command)
  File "/usr/lib/python3.8/subprocess.py", line 858, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,
  File "/usr/lib/python3.8/subprocess.py", line 1704, in _execute_child
    raise child_exception_type(errno_num, err_msg, err_filename)
FileNotFoundError: [Errno 2] No such file or directory: 'tmserver'

I guess it's an improvement compared to Ubuntu 18.04 LTS where Virtaal didn't even start at all but having this kind of broken package in Ubuntu is no good.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: virtaal 0.7.1+git20191021+ds1-1 [modified: usr/lib/python3/dist-packages/virtaal/support/set_enumerator.py]
ProcVersionSignature: Ubuntu 5.15.0-58.64~20.04.1-lowlatency 5.15.74
Uname: Linux 5.15.0-58-lowlatency x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.25
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: MATE
Date: Wed Jan 25 16:53:53 2023
EcryptfsInUse: Yes
InstallationDate: Installed on 2019-01-05 (1480 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
PackageArchitecture: all
SourcePackage: virtaal
UpgradeStatus: Upgraded to focal on 2022-09-13 (133 days ago)
modified.conffile..etc.init.d.apport: [modified]
mtime.conffile..etc.init.d.apport: 2022-05-19T12:50:20.029158