PVS-Studio warning V541 for Scilab

static int sci_toprint_two_rhs(void* _pvCtx,
                               const char *fname)
{
  ....
  sprintf(lines, "%s%s\n", lines, pStVarOne[i]);
  ....
}

This suspicious code was found in Scilab project by PVS-Studio static code analyzer.
Warning message is:
V541 It is dangerous to print the string 'lines' into itself. sci_toprint.cpp 314

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/