merges r30721 from trunk into ruby_1_9_2.

--
* array.c (rb_ary_join): [].join.encoding must be US-ASCII.
  [ruby-list:47790]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_2@30901 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 1 insertions, 1 deletions

diff --git a/array.c b/array.c
index d413f3377f..6640a1af28 100644
--- a/array.c
+++ b/array.c
@@ -1643,7 +1643,7 @@ rb_ary_join(VALUE ary, VALUE sep)
     int untrust = FALSE;
     VALUE val, tmp, result;
 
-    if (RARRAY_LEN(ary) == 0) return rb_str_new(0, 0);
+    if (RARRAY_LEN(ary) == 0) return rb_usascii_str_new(0, 0);
     if (OBJ_TAINTED(ary) || OBJ_TAINTED(sep)) taint = TRUE;
     if (OBJ_UNTRUSTED(ary) || OBJ_UNTRUSTED(sep)) untrust = TRUE;