bug#19420: intermittent segfault using grep -P

[Paul Eggert]

I can't reproduce the problem on Ubuntu 14.10 (x86-64) or Fedora 20 (x86-64), 
with either the bundled grep or with GNU grep 2.21.

What locale are you running in?  What's the output of the 'locale' command?

It could be a bug in grep, or in libpcre, or somewhere else.  Ubuntu 14.10 is 
running libpcre3 1:8.35-3ubuntu1.  I vaguely recall that they're doing something 
funky to prevent grep from depending on libpcre while still supporting -P, but I 
don't recall the details.