PVS-Studio warning V579 for TortoiseSVN

int  AffixMgr::parse_convtable(...., const char * keyword)
{
  char * piece;
  ....
  if (strncmp(piece, keyword, sizeof(keyword)) != 0) {
  ....
}

This suspicious code was found in TortoiseSVN project by PVS-Studio static code analyzer.
Warning message is:
V579 The strncmp function receives the pointer and its size as arguments. It is possibly a mistake. Inspect the third argument. affixmgr.cxx 3654

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