PVS-Studio warning V637 for Virtualdub

void VDBackfaceService::Execute(
  IVDBackfaceStream& out, char *s)
{
  ....
  if (*s == '"') {
    while(*s && *s != '"')
      ++s;
  } else {
  ....
}

This suspicious code was found in Virtualdub project by PVS-Studio static code analyzer.
Warning message is:
V637 Two opposite conditions were encountered. The second condition is always false. Check lines: 183, 184. VirtualDub backface.cpp 183

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