put fix_pyver before printing command help

If pyver forces koji to reload under different interpreter, it could
happen, that different set of plugins is available. In such case help
printed under original interpreter can be misleading.

Fixes: https://pagure.io/koji/issue/1276

cli/koji

@@ -167,12 +167,11 @@ def get_options():
                    (sys.prefix, sys.version_info[0], sys.version_info[1])
     load_plugins(options, plugins_path)
 
-    if options.help_commands:
-        list_commands()
-        sys.exit(0)
     if not args:
-        list_commands()
-        sys.exit(0)
+        options.help_commands = True
+    if options.help_commands:
+        # hijack args to [return_code, message]
+        return options, '_list_commands', [0, '']
 
     aliases = {
         'cancel-task' : 'cancel',
@@ -199,9 +198,8 @@ def get_options():
     elif ('handle_' + cmd) in globals():
         cmd = 'handle_' + cmd
     else:
-        list_commands()
-        parser.error('Unknown command: %s' % args[0])
-        assert False  # pragma: no cover
+        # hijack args to [return_code, message]
+        return options, '_list_commands', [1, 'Unknown command: %s' % args[0]]
 
     return options, cmd, args[1:]
 
@@ -305,6 +303,12 @@ if __name__ == "__main__":
 
     session_opts = koji.grab_session_options(options)
     session = koji.ClientSession(options.server, session_opts)
+    if command == '_list_commands':
+        list_commands()
+        if args[0] != 0:
+            logger.error(args[1])
+        sys.exit(args[0])
+    # run handler
     rv = 0
     try:
         rv = locals()[command].__call__(options, session, args)