[exim] minor bug

Hi!

Sometimes exim 4.42 crashes by segfault if log selector
return_path_on_delivery switched on.
I think the error is in deliver.c, lines 864-865:

  if ((log_extra_selector & LX_return_path_on_delivery) != 0)
    s = string_append(s, &size, &ptr, 3, US" P=<", used_return_path, US">");

used_return_path can be NULL, as we can see below, lines 1102-1108
in the same function:

/* Return path may not be set if no delivery actually happened */

  if (used_return_path != NULL &&
      (log_extra_selector & LX_return_path_on_delivery) != 0)
    {
    s = string_append(s, &size, &ptr, 3, US" P=<", used_return_path, US">");
    }

And another thing:
smtp_in.c, line 1482 - IMHO a space at start of the line
" temporarily refused connection ..." is odd. ;-)

-- 
                                Lucky carrier,
                                                  Pavel.