Build of 7.8.866 getting stuck in a loop

[Magnus Holmgren, Millnet/Lysator/Debian/Mensa @ Pike developers forum]

PEEP at 468: nop => 
PEEP at 468: nop => 
PEEP at 470: mark global(2) =>  mark & global(2)
PEEP at 471: assign local and pop(1) local(1) =>  assign local(1)
PEEP at 471: push int(0) =>  push 0
PEEP at 471: push 0 index =>  int index(0)
PEEP at 472: mark local(1) =>  mark & local(1)
PEEP at 473: mark call builtin(23) =>  mark, call builtin(23)
PEEP at 474: push 0 assign local and pop(5) =>  clear local(5)
PEEP at 474: clear local(5) & local(5) =>  & local(5) clear local(5)
PEEP at 475: local(5) clear string subtype index =>  local index(5)
PEEP at 475: global(3) local index(5) =>  global[local](3,5)
PEEP at 476: mark global(3) =>  mark & global(3)
PEEP at 476: local(5) clear string subtype index =>  local index(5)
PEEP at 477: mark local(5) =>  mark & local(5)
PEEP at 477: local(5) clear string subtype index =>  local index(5)
PEEP at 477: global(3) local index(5) =>  global[local](3,5)
PEEP at 474: nop => 
PEEP at 474: nop => 
PEEP at 479: call builtin 1(24) pop =>  call builtin1 & pop(24)
PEEP at 480: push 0 assign local and pop(5) =>  clear local(5)
PEEP at 480: clear local(5) & local(5) =>  & local(5) clear local(5)
PEEP at 481: mark local(5) =>  mark & local(5)
PEEP at 481: local(3) local(5) =>  2 locals(3,5)
PEEP at 481: 2 locals(3,5) clear string subtype index =>  local[local](5,3)
PEEP at 482: push int(0) =>  push 0
PEEP at 482: push 0 index =>  int index(0)
PEEP at 483: local(4) local(5) =>  2 locals(4,5)
PEEP at 483: push int(1) =>  push 1
PEEP at 483: push 1 index =>  int index(1)
PEEP at 480: nop => 
PEEP at 480: nop => 
PEEP at 487: push 0 assign local and pop(5) =>  clear local(5)
PEEP at 487: clear local(5) & local(5) =>  & local(5) clear local(5)
PEEP at 488: mark string(147) =>  mark & string(147)
PEEP at 489: local(4) local(5) =>  2 locals(4,5)
PEEP at 489: 2 locals(4,5) clear string subtype index =>  local[local](5,4)
PEEP at 487: nop => 
PEEP at 487: nop => 
PEEP at 490: push 0 assign local and pop(5) =>  clear local(5)
PEEP at 490: clear local(5) & local(5) =>  & local(5) clear local(5)
PEEP at 491: local(5) clear string subtype index =>  local index(5)
PEEP at 491: global(5) local index(5) =>  global[local](5,5)
PEEP at 492: assign local and pop(6) local(6) =>  assign local(6)
PEEP at 492: push int(-2147483648) =>  push -int(-2147483648)
PEEP at 492: push -int(-2147483648) =>  push int(-2147483648)
PEEP at 492: push int(-2147483648) =>  push -int(-2147483648)
PEEP at 492: push -int(-2147483648) =>  push int(-2147483648)
... ad infinitum.

So an integer overflow, but why?