"0 0" return tag

I have updated the attached C comment about why we return "0 0" for some
tags.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +
Index: src/backend/tcop/pquery.c
===================================================================
RCS file: /cvsroot/pgsql/src/backend/tcop/pquery.c,v
retrieving revision 1.134
diff -c -c -r1.134 pquery.c
*** src/backend/tcop/pquery.c    2 Jan 2010 16:57:52 -0000    1.134
--- src/backend/tcop/pquery.c    13 Feb 2010 22:45:08 -0000
***************
*** 1318,1326 ****
       * If a command completion tag was supplied, use it.  Otherwise use the
       * portal's commandTag as the default completion tag.
       *
!      * Exception: clients will expect INSERT/UPDATE/DELETE tags to have
!      * counts, so fake something up if necessary.  (This could happen if the
!      * original query was replaced by a DO INSTEAD rule.)
       */
      if (completionTag && completionTag[0] == '\0')
      {
--- 1318,1331 ----
       * If a command completion tag was supplied, use it.  Otherwise use the
       * portal's commandTag as the default completion tag.
       *
!      * Exception: Clients expect INSERT/UPDATE/DELETE tags to have
!      * counts, so fake them with zeros.  This can happen with DO INSTEAD
!      * rules if there is no replacement query of the same type as the
!      * original.  We print "0 0" here because technically there is no
!      * query of the matching tag type, and printing a non-zero count for
!      * a different query type seems wrong, e.g.  an INSERT that does
!      * an UPDATE instead should not print "0 1" if one row
!      * was updated.  See QueryRewrite(), step 3, for details.
       */
      if (completionTag && completionTag[0] == '\0')
      {