Fix bug in flag checking for --no-*.

include/program_args/arguments_impl.hpp

@@ -125,7 +125,7 @@ Arguments<Impl>::Arguments(int argc, char const * const * const argv) {
     } else if (arg[0] != '-') {
       arguments.emplace_back(arg);
     } else if (is_flag(arg)) {
-      if (arg.substr(0, 4) == "--no-") {
+      if (arg.substr(0, 5) == "--no-") {
         flags[id(arg)] = 0;
       } else {
         ++flags[id(arg)];