gnome client: be sure key exchange is set correctly

gnome/src/config/accountconfigdialog.c

@@ -1399,8 +1399,10 @@ void show_account_window(account_t * currentAccount)
             g_hash_table_replace(currentAccount->properties, g_strdup(ACCOUNT_SRTP_ENABLED), g_strdup("true"));
             g_hash_table_replace(currentAccount->properties, g_strdup(ACCOUNT_KEY_EXCHANGE), g_strdup(SDES));
         }
-        else
+        else {
             g_hash_table_replace(currentAccount->properties, g_strdup(ACCOUNT_SRTP_ENABLED), g_strdup("false"));
+            g_hash_table_replace(currentAccount->properties, g_strdup(ACCOUNT_KEY_EXCHANGE), g_strdup(""));
+        }
 
         g_free(keyExchange);