bug#9087: Crash reading from minibuffer with icomplete-mode

[Eli Zaretskii]

> From: Juanma Barranquero <lekktu@gmail.com>
> Date: Fri, 15 Jul 2011 14:11:22 +0200
> Cc: 9087@debbugs.gnu.org
> 
> #0  w32_abort () at w32fns.c:7182
> #1  0x0103a942 in xfree (block=0x32d4f80) at alloc.c:713

AFAIU, this abort means that we call UNBLOCK_INPUT without a paired
BLOCK_INPUT.

Could you perhaps repeat the recipe after setting a watchpoint on the
variable interrupt_input_blocked, with commands like this:

  p interrupt_input_blocked
  bt 5
  continue

Then GDB should show who calls BLOCK_INPUT and UNBLOCK_INPUT, and if
we are lucky, we will see the unpaired call.