Fix empty unknown option name in OptionParser::parse

src/OptionParser.cc

@@ -247,7 +247,6 @@ void OptionParser::parse(Option& option, std::istream& is) const
 
 void OptionParser::parse(Option& option, const KeyVals& options) const
 {
-  std::string line;
   for(KeyVals::const_iterator i = options.begin(), eoi = options.end();
       i != eoi; ++i) {
     const Pref* pref = option::k2p((*i).first);
@@ -255,7 +254,7 @@ void OptionParser::parse(Option& option, const KeyVals& options) const
     if(handler) {
       handler->parse(option, (*i).second);
     } else {
-      A2_LOG_WARN(fmt("Unknown option: %s", line.c_str()));
+      A2_LOG_WARN(fmt("Unknown option: %s", (*i).first.c_str()));
     }
   }
 }