views: Make session form easier to understand

Show a more detailed description of each choice

Display an error and redirect the user if an empty list of os's was
received. Post does not work with an empty list

ogcp/views.py

@@ -838,9 +838,14 @@ def action_session():
         form.ips.data = ' '.join(ips)
         r = server.get('/session', payload={'client': list(ips)})
         sessions = r.json()['sessions']
+        if not sessions:
+            flash(_('ogServer returned an empty session list'),
+              category='error')
+            return redirect(url_for('commands'))
+
         for os in sessions:
             choice = (f"{os['disk']} {os['partition']}",
-                      f"{os['name']} ({os['disk']},{os['partition']})")
+                      f"OS: {os['name']} (Disk:{os['disk']}, Partition:{os['partition']})")
             form.os.choices.append(choice)
         scopes, clients = get_scopes(set(ips))
         selected_clients = list(get_selected_clients(scopes['scope']).items())