pg_resetxlog defect with relative database path

When I was testing pg_resetxlog with relative database path,
The pg_resetxlog is doing the transaction log reset even when the server is
running.

Steps to reproduce:
1. ./pg_ctl -D ../../data start
2. ./pg_resetxlog -f ../../data -- is not able to detect as server
is already running.

Please find the patch for the same:

*** a/src/bin/pg_resetxlog/pg_resetxlog.c
--- b/src/bin/pg_resetxlog/pg_resetxlog.c
***************
*** 254,260 **** main(int argc, char *argv[])
*/
snprintf(path, MAXPGPATH, "%s/postmaster.pid", DataDir);

! if ((fd = open(path, O_RDONLY, 0)) < 0)
{
if (errno != ENOENT)
{
--- 254,260 ----
*/
snprintf(path, MAXPGPATH, "%s/postmaster.pid", DataDir);

! if ((fd = open("postmaster.pid", O_RDONLY, 0)) < 0)
{
if (errno != ENOENT)
{

Any suggestions/comments?

Regards,
Hari babu.