Fix a regression that broke kitten_alias

Fixes #2952

docs/changelog.rst

@@ -44,6 +44,8 @@ To update |kitty|, :doc:`follow the instructions <binary>`.
   Plex Mono and have the regular face with a full name that is the same as the
   family name (:iss:`2951`)
 
+- Fix a regression that broke :opt:`kitten_alias` (:iss:`2952`)
+
 
 0.18.3 [2020-08-11]
 -------------------

kitty/config.py

@@ -393,7 +393,7 @@ def resolve_kitten_aliases(self, aliases: Dict[str, Sequence[str]]) -> None:
                 if len(expanded) > 1:
                     rest = expanded[1] + ' ' + rest
         if changed:
-            self.action = self.action._replace(args=[kitten + (' ' + rest).rstrip()])
+            self.action = self.action._replace(args=[kitten, rest.rstrip()])
 
 
 def parse_key(val: str, key_definitions: List[KeyDefinition]) -> None: