Merge pull request #649 from masamitsu-murase/fix_string_bytes

Modify String#bytes.

src/string.c

@@ -2997,7 +2997,7 @@ mrb_str_bytes(mrb_state *mrb, mrb_value str)
 {
   struct RString *s = mrb_str_ptr(str);
   mrb_value a = mrb_ary_new_capa(mrb, s->len);
-  char *p = s->ptr, *pend = p + s->len;
+  unsigned char *p = (unsigned char *)(s->ptr), *pend = p + s->len;
 
   while (p < pend) {
     mrb_ary_push(mrb, a, mrb_fixnum_value(p[0]));

test/t/string.rb

@@ -369,7 +369,10 @@ assert('String#bytes') do
   str1 = "hello"
   bytes1 = [104, 101, 108, 108, 111]
 
-  str1.bytes == bytes1
+  str2 = "\xFF"
+  bytes2 = [0xFF]
+
+  str1.bytes == bytes1 and str2.bytes == bytes2
 end
 
 assert('String#each_byte') do