PVS-Studio warning V564 for FFMpeg

static int dca_subsubframe(DCAContext *s,
  int base_channel, int block_index)
{
  ....
  if (!s->debug_flag & 0x01) {
    av_log(s->avctx, AV_LOG_DEBUG,
      "Stream with high frequencies VQ coding\n");
    s->debug_flag |= 0x01;
  }
  ....
}

This suspicious code was found in FFMpeg project by PVS-Studio static code analyzer.
Warning message is:
V564 The '&' operator is applied to bool type value. You've probably forgotten to include parentheses or intended to use the '&&' operator. dcadec.c 1373

PVS-Studio is a static analyzer for detecting bugs in the source code of applications written in C, C++, C++11, C++/CX. Site: http://www.viva64.com/en/pvs-studio/