rational.c: simplify a branch condition

* rational.c (nurat_s_convert): simplify a branch condition.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62564 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

rational.c

@@ -2620,7 +2620,7 @@ nurat_s_convert(int argc, VALUE *argv, VALUE klass)
     }
 
     if (argc == 1) {
-	if (!(k_numeric_p(a1) && k_integer_p(a1)))
+	if (!k_integer_p(a1))
 	    return rb_convert_type_with_id(a1, T_RATIONAL, "Rational", idTo_r);
     }
     else {