nsfarm/lxd/utils: fix PermissionError on container clean

The user might not have ability to send signal to that process but we
only check if process exists (is running) and not having ability means
that process is running.

nsfarm/lxd/utils.py

@@ -79,7 +79,9 @@ def clean_containers(dry_run=False):
             try:
                 os.kill(pid, 0)
             except OSError as err:
-                if (err.errno != 3):  # 3 == ESRCH: No such process
+                if err.errno == 1:  # 1 == EPERM: Process is running under different user
+                    continue
+                if err.errno != 3:  # 3 == ESRCH: No such process
                     raise
                 removed.append(cont.name)
                 if not dry_run: