PVS-Studio warning V561 for FlightGear

void DCLGPS::update(double dt) {
  ....
  string s;
  if(fgGetBool("/instrumentation/nav[0]/slaved-to-gps")) {
    // TODO - avoid the hardwiring on nav[0]
    s = "Adj Nav Crs to ";
  } else {
    string s = "GPS Course is ";
  }
  ....
}

This suspicious code was found in FlightGear project by PVS-Studio static code analyzer.
Warning message is:
V561 It's probably better to assign value to 's' variable than to declare it anew. Previous declaration: dclgps.cxx, line 480. dclgps.cxx 485

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/