Patch to Ruby in 2005

According to the ChangeLog in Ruby 1.8.4 the 
following patch was made to Ruby in 2005

Wed Jun  8 08:33:10 2005  Nobuyoshi Nakada  <nobu@ruby-
lang.org>
* eval.c (backtrace): skip successive frames sharing same node. 

We are having some trouble as a result, because when using the 
coerce feature of ruby, the call stack no longer contains the 
information needed, and we have traced this to a line of code in
backtrace in eval.c.

 if (frame->prev->node == n) continue;

If this is commented out then the problem goes away.

The problem is that the calling operator e.g. `+' is no longer in the
string given by caller[0] and so it is not possible to take different
action depending on different operators.

For more details please see the discussion on

http://c2.com/cgi/wiki?ElizabethWiethoff

Please would you consider reversing this change or else modifying 
it
so that the previous behaviour is restored for coerce.

Example code for what is being done is on 

http://c2.com/cgi/wiki?RubyCoerce

I guess that there may be other reasons why you made the change.

Thank you

John Fletcher
-- 
Dr John P. Fletcher   Tel: [phone] (direct line)
Chemical Engineering and Applied Chemistry (CEAC),
School of Engineering and Applied Science (SEAS),
Aston University, Aston Triangle, BIRMINGHAM B4 7ET  U.K.               
CEAC Web site http://www.ceac.aston.ac.uk/
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