merges r23773 from trunk into ruby_1_9_1.

--
* transcode.c (enc_arg): default interanl encoding may not be set.
  [ruby-core:23932]

git-svn-id: http://svn.ruby-lang.org/repos/ruby/branches/ruby_1_9_1@23807 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 2 deletions

diff --git a/transcode.c b/transcode.c
index 18ddd5fd4..7eb2220cc 100644
--- a/transcode.c
+++ b/transcode.c
@@ -2394,13 +2394,13 @@ enc_arg(volatile VALUE *arg, const char **name_p, rb_encoding **enc_p)
     int encidx;
     VALUE encval;
 
-    if ((encidx = rb_to_encoding_index(encval = *arg)) < 0) {
+    if (((encidx = rb_to_encoding_index(encval = *arg)) < 0) ||
+	!(enc = rb_enc_from_index(encidx))) {
 	enc = NULL;
 	encidx = 0;
 	n = StringValueCStr(*arg);
     }
     else {
-	enc = rb_enc_from_index(encidx);
 	n = rb_enc_name(enc);
     }