R devel - Oct 2003 - no traceback in R-patched

Has something changed with traceback's in R-patched?  When I running the 
examples for ?traceback, I get
>      foo <- function(x) { print(1); bar(2) }
>      bar <- function(x) { x + a.variable.which.does.not.exist }
>     foo(2) # gives a strange error
[1] 1
Error in bar(2) : Object "a.variable.which.does.not.exist" not
found
>  traceback()
No traceback available
>
It seems the .Traceback variable is never created.
>  version
         _               
platform i686-pc-linux-gnu
arch     i686            
os       linux-gnu       
system   i686, linux-gnu 
status   alpha           
major    1               
minor    8.1             
year     2003            
month    10              
day      28              
language R               

-roger

Since it's heading towards release, I thought I'd bring this up again. 
I'm still not getting any traceback()'s in recent R-patched.  For 
example, I get:

 > log("a")
Error in log(x) : Non-numeric argument to mathematical function
 > traceback()
No traceback available

Or when running the examples in the traceback() help page:

 >      foo <- function(x) { print(1); bar(2) }
 >      bar <- function(x) { x + a.variable.which.does.not.exist }
 >      ## Don't run:
 >      foo(2) # gives a strange error
[1] 1
Error in bar(2) : Object "a.variable.which.does.not.exist" not found
 >      traceback()
No traceback available

It seems the .Traceback variable is not being created.  If I'm doing 
something incorrectly, I'd very much like to know.  I'm starting up with
R --vanilla.

 > version
          _
platform i686-pc-linux-gnu
arch     i686
os       linux-gnu
system   i686, linux-gnu
status   alpha
major    1
minor    8.1
year     2003
month    11
day      07
language R
 > search()
[1] ".GlobalEnv"      "package:methods"
"package:ctest"   "package:mva"
[5] "package:modreg"  "package:nls"    
"package:ts"      "Autoloads"
[9] "package:base"
 >


-roger