Change the way DebOps checks current user

The 'os.getlogin()' function relies on the glibc 'getlogin()' function,
which requires a control terminal (tty, pty) to work. In an environment
without the control terminal (systemd service, remote execution) it
results in the 'OSError: [Errno 6] No such device or address' exception.

Switching to 'getpass.getuser()' function is a recommended alternative.

src/debops/cli.py

@@ -10,6 +10,7 @@
 from .ansibleplaybookrunner import AnsiblePlaybookRunner
 from .envrunner import EnvRunner
 import logging
+import getpass
 import sys
 import os
 
@@ -23,7 +24,7 @@ def __init__(self, args=None):
         self.config = Configuration()
         self.parsed_args = Subcommands(self.args)
         logger.debug('Command line interpreter initialized')
-        logger.debug('Control user=' + os.getlogin())
+        logger.debug('Control user=' + getpass.getuser())
 
         if self.parsed_args.section == 'project':
             if self.parsed_args.command == 'init':