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 start2. ./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.