Hello,

I've found the following (extracted & abstacted from part of rails)  
causes a crash on the latest ruby (compiled a few minutes ago)

counter = 2
while true
   counter -= 1
   next if counter != 0
   break
end

This outputs

crash.rb:5: -- control frame ----------
c:0003 p:0026 s:0007 b:0006 l:000005 d:000005 TOP    crash.rb:5
c:0002 p:---- s:0003 b:0003 l:000002 d:000002 FINISH :inherited
c:0001 p:---- s:0001 b:-001 l:000000 d:000000 ------
---------------------------
-- backtrace of native function call (Use addr2line) --
0xdae76
0x1aca5
0x1ad4b
0xd8dac
0xd950c
0xd97d9
0x1e1c4
0x22d3a
0x198f
0x18f6
-------------------------------------------------------
[BUG] Stack consistency error (sp: 7, bp: 6)
ruby 1.9.0 (2007-12-24) [i686-darwin9.1.0]

I've no idea why this happens, hopefully someone who understands ruby  
better than I do can pick this one apart.

Fred