fix(_known_hosts): work around localvar_inherit

Author: akinomyoga

bash_completion

@@ -1816,7 +1816,7 @@ _known_hosts()
 
     # NOTE: Using `_known_hosts' as a helper function and passing options
     #       to `_known_hosts' is deprecated: Use `_known_hosts_real' instead.
-    local options
+    local options=""
     [[ ${1-} == -a || ${2-} == -a ]] && options=-a
     [[ ${1-} == -c || ${2-} == -c ]] && options+=" -c"
     # shellcheck disable=SC2086