commit 775f7bf1b80a2db04c05793e78769c13bb48822c
Author: Stefan Kaes <skaes@railsexpress.de>
Date:   Sun Apr 14 07:42:31 2013 +0200

    display full backtrace on stack overflow

diff --git a/eval.c b/eval.c
index 79f4a0a..271eff3 100644
--- a/eval.c
+++ b/eval.c
@@ -454,8 +454,7 @@ setup_exception(rb_thread_t *th, int tag, volatile VALUE mesg)
     if (file) line = rb_sourceline();
     if (file && !NIL_P(mesg)) {
 	if (mesg == sysstack_error) {
-	    at = rb_enc_sprintf(rb_usascii_encoding(), "%s:%d", file, line);
-	    at = rb_ary_new3(1, at);
+	    at = rb_make_backtrace();
 	    rb_iv_set(mesg, "bt", at);
 	}
 	else {