client: make error a bit more helpful

If a Place has multiple SSH targets, typing "labgrid-client ssh <net-name>"
triggers an ambiguous "multiple targets" error. It's usually just a missing
-n flag, so let's point the user in the right direction with a clearer hint
in the logs.

Signed-off-by: Lothar Rubusch <l.rubusch@gmail.com>

Author: Rubusch

labgrid/remote/client.py

@@ -1308,6 +1308,10 @@ def _get_ssh(self):
             return drv
 
     def ssh(self):
+        if self.args.leftover and not self.args.name:
+            potential_name = self.args.leftover[0]
+            print(f"Unknown argument '{potential_name}', did you miss a '-n'?")
+
         drv = self._get_ssh()
 
         res = drv.interact(self.args.leftover)