[testcase] regex hang

[Gwenole Beauchesne]

Hi,

> With this testcase, regexec goes very deep recursion from
> prune_impossible_nodes -> sift_states_backward and stays that way
> until killed.

As a reminder, a similar bug is:
<http://sources.redhat.com/ml/libc-alpha/2003-01/msg00199.html>

Thanks,
Gwenole