From: Phil Thompson <phil@river-bank.demon.co.uk>

I haven't had final confirmation from Peter yet, but the attached patch
needs to be applied for the Beta otherwise password and crypt
authentication just won't work.

It puts back the loop in libpq and also fixes a couple of problems with
maintaining compatability with pre-6.3 drivers.

src/backend/libpq/crypt.c

@@ -271,7 +271,7 @@ int crypt_verify(Port* port, const char* user, const char* pgpass) {
   if (!strcmp(pgpass, crypt_pwd)) {
     /* check here to be sure we are not past valuntil
      */
-    if (!valuntil)
+    if (!valuntil || strcmp(valuntil, "\\N") == 0)
       vuntil = INVALID_ABSTIME;
     else
       vuntil = nabstimein(valuntil);