stringio.c: keep coderange

* ext/stringio/stringio.c (strio_write): keep coderange of
  ptr->string.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41721 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 1 insertions, 1 deletions

diff --git a/ext/stringio/stringio.c b/ext/stringio/stringio.c
index d15db8b076..57854919cd 100644
--- a/ext/stringio/stringio.c
+++ b/ext/stringio/stringio.c
@@ -1182,7 +1182,7 @@ strio_write(VALUE self, VALUE str)
 	ptr->pos = olen;
     }
     if (ptr->pos == olen) {
-	rb_str_cat(ptr->string, RSTRING_PTR(str), len);
+	rb_enc_str_buf_cat(ptr->string, RSTRING_PTR(str), len, enc);
     }
     else {
 	strio_extend(ptr, ptr->pos, len);