pylint: Fix several warnings

Fixes Pylint warnings:
- R1729(use-a-generator)
- R1710(inconsistent-return-statements)
- R1727(condition-evals-to-constant)

Fixes: https://pagure.io/freeipa/issue/8772
Signed-off-by: Stanislav Levin <slev@altlinux.org>
Reviewed-By: Alexander Bokovoy <abokovoy@redhat.com>

ipapython/install/cli.py

@@ -329,6 +329,8 @@ class ConfigureTool(admintool.AdminTool):
         except RuntimeError as e:
             self.option_parser.error(str(e))
 
+        return None
+
     def run(self):
         cfgr = self.init_configurator()