[tests] Finally get rid of the assert failure in oracle of empty3.cpp

framaCIRGen_src/ACSLLexer.cpp

@@ -1890,6 +1890,7 @@ void Lexer::handlePPDirectiveInACSL(const std::string& buffer, size_t& position,
 // FIXME - not valid if there is a # immediately followed by newline
 void
 Lexer::removeFromRevision(size_t start) {
+  if (start+1>= _revised.size()) { _revised[start] = ' '; return; }
   if (_revised[start+1] == '\n') {
     _revised[start] = ' ';
   } else {