lxmf_cmd does not work, wrong system function call is used causing exception

[radio-miskovice]

The application never gets to execution of any command because wrong function call causes OSError being thrown.

[2025-11-07 06:57:53] [Debug] LXMF - Call to registered message received callback
[2025-11-07 06:57:53] [Error]    An error occurred in the external delivery callback for <LXMessage bcd6395ce9b0144b5934ea3a1bf5bb48bb1c80e469c211ce6eab5012caf53d30>
[2025-11-07 06:57:53] [Error]    An unhandled <class 'OSError'> exception occurred: [Errno 6] No such device or address
[2025-11-07 06:57:53] [Error]    Traceback (most recent call last):
  File "/usr/local/lib/python3.11/dist-packages/LXMF/LXMRouter.py", line 1787, in lxmf_delivery
    self.__delivery_callback(message)
  File "/home/dietpi/LXMF-Tools/lxmf_cmd/lxmf_cmd.py", line 653, in process_lxmf_message_propagated
    self.message_received_callback(message)
  File "/home/dietpi/LXMF-Tools/lxmf_cmd/lxmf_cmd.py", line 832, in lxmf_message_received_callback
    content_prefix = replace(content_prefix)
                     ^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/dietpi/LXMF-Tools/lxmf_cmd/lxmf_cmd.py", line 854, in replace
    text = text.replace("!user!", os.getlogin())
                                  ^^^^^^^^^^^^^
OSError: [Errno 6] No such device or address

The issue is described here: python/cpython#84998

Instead, it is recommended to use getpass.getuser()

My environment:
DietPi Linux 6.1.115-vendor-rk35xx #1 aarch64
Python 3.11.2

[radio-miskovice]

Solution proposal:

1. add import getpass in the include section
2. at original line 853 (after adding the import it will be line 854) replace os.getlogin() by getpass.getuser()

[radio-miskovice]

Permanent solution would be to add try/catch block and use either of the system calls that works.