Infinite loop when processing backreferences

What steps will reproduce the problem?

Using Python 3.4:
import regex
r = regex.compile(r'\bof ([a-z]+) of \1\b')
r.findall("To make use of one of these modules")

What is the expected output? What do you see instead?
I expect the program to halt eventually. All I see is a blinking cursor in my 
terminal.

Which version of Python? 32-bit or 64-bit?
Python 3.4.1 and 2.7.8, x86-64, Arch Linux.

Please provide any additional information below.

PS: Thanks a lot for working on improving Python regex support. I wrote Topy, 
which uses regexps to fix common misspellings/grammar errors in text 
(https://github.com/intgr/topy). Python's built-in regex engine is too limited 
for this ruleset, so +1 for merging this into Python.

Original issue reported on code.google.com by ma...@juffo.org on 15 Aug 2014 at 12:21

jamadden / mrab-regex-hg

Infinite loop when processing backreferences #115