merges r24015 from trunk into ruby_1_9_1.

--
* marshal.c (r_object0): set encoding only if the encoding is not US-ASCII.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_1@24079 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 1 deletions

diff --git a/marshal.c b/marshal.c
index cbed195b5b..860b23f11b 100644
--- a/marshal.c
+++ b/marshal.c
@@ -1376,7 +1376,8 @@ r_object0(struct load_arg *arg, int *ivp, VALUE extmod)
 		r_ivar(v, arg);
 		*ivp = Qfalse;
 	    }
-	    rb_enc_copy(str, v);
+	    if (rb_enc_get_index(v) != rb_usascii_encindex())
+		rb_enc_copy(str, v);
 	    if (rb_enc_get_index(str) != rb_utf8_encindex()) {
 #define f_gsub_bang(x,y,z) rb_funcall(x, rb_intern("gsub!"), 2, y, z)
 		f_gsub_bang(str, rb_reg_new("\\\\u", 3, 0), rb_usascii_str_new_cstr("u"));