calibre-web: upload ebook failure

[Nigatsu]

When trying to upload an ebook I get 500 error:

The server encountered an internal error and was unable to complete your request. There is an error in the application.

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/dist-packages/flask/app.py", line 2190, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python3.8/dist-packages/flask/app.py", line 1486, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python3.8/dist-packages/flask/app.py", line 1484, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python3.8/dist-packages/flask/app.py", line 1469, in dispatch_request
    return self.ensure_sync(self.view_functions[rule.endpoint])(**view_args)
  File "/tmp/calibre-web/cps/usermanagement.py", line 35, in decorated_view
    return login_required(func)(*args, **kwargs)
  File "/usr/local/lib/python3.8/dist-packages/flask_login/utils.py", line 290, in decorated_view
    return current_app.ensure_sync(func)(*args, **kwargs)
  File "/tmp/calibre-web/cps/editbooks.py", line 59, in inner
    return f(*args, **kwargs)
  File "/tmp/calibre-web/cps/editbooks.py", line 249, in upload
    meta, error = file_handling_on_upload(requested_file)
  File "/tmp/calibre-web/cps/editbooks.py", line 755, in file_handling_on_upload
    if not validate_mime_type(requested_file, allowed_extensions):
  File "/tmp/calibre-web/cps/file_helper.py", line 49, in validate_mime_type
    mime = magic.Magic(mime=True)

NameError: name 'magic' is not defined

It's probably related to not up-to-date python inside elfhosted/containers/calibre-web image. A similar problem was discussed on calibre-web repo.
Tried to use linuxserver/calibre-web image as a custom app and it worked flawlessly.