BUG in XLogRecordAssemble

hi,
   I found the code in 'backend/access/transam/xloginsert.c' as that:
XLogRecordAssemble:
 if (prev_regbuf && RelFileNodeEquals(regbuf->rnode, prev_regbuf->rnode))
        {
            samerel = true;
            bkpb.fork_flags |= BKPBLOCK_SAME_REL;
            prev_regbuf = regbuf;
        }
        else
            samerel = false;

There is the only place that prev_regbuf is assigned, so prev_regbuf will never be assigned.
The patch will fix it, Thanks.
                                                                                                                  Zhang Zq