Minor cleanup for commit dd7cf6c.

* src/agent.c (pksign_parse_result): Remove leading Nul byte only if
it is a suffix.
--

Signed-off-by: Werner Koch <wk@gnupg.org>

src/agent.c

@@ -1026,7 +1026,7 @@ pksign_parse_result (const struct signature *sig,
     return gpg_error (GPG_ERR_INV_SEXP);
 
   /* Remove nul byte prepended by gpg-agent. */
-  if (*s == 0)
+  if (!*s && n > 1)
     {
       n -= 1;
       s += 1;