Encoding.default_internal should affect ENV on Windows like other platforms

* hash.c (env_str_transcode): call rb_external_str_with_enc() if
  default_internal is available.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58687 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

hash.c

@@ -3070,8 +3070,15 @@ extern char **environ;
 static VALUE
 env_str_transcode(VALUE str, rb_encoding *enc)
 {
-    return rb_str_conv_enc_opts(str, NULL, enc,
-				ECONV_INVALID_REPLACE | ECONV_UNDEF_REPLACE, Qnil);
+    rb_encoding *internal = rb_default_internal_encoding();
+    if (!internal) {
+	return rb_str_conv_enc_opts(str, NULL, enc,
+				    ECONV_INVALID_REPLACE | ECONV_UNDEF_REPLACE,
+				    Qnil);
+    }
+    else {
+	return rb_external_str_with_enc(str, rb_utf8_encoding());
+    }
 }
 #endif